The UK Crown Prosecution Service (CPS) has announced that Sir Mark Allen, the former head of MI6’s counterterrorism operations, and then Labour Foreign Secretary Jack Straw will not face criminal charges for their role in the illegal rendition and torture of Libyan dissidents.

Its decision flies in the face of the overwhelming evidence of Britain’s involvement at the very highest level in the rendition and torture of two Libyan Islamist dissidents in 2004. Just days later, the Guardian reported that the government had, as of last September, spent at least £600,000 in an effort to prevent a civil case going ahead, forcing Straw and Allen to give evidence.

Abdel Hakim Belhaj, a Libyan Islamist opposed to former leader Muammar Gaddafi, and his wife, are suing the then Labour government, the foreign secretary and the head of Britain’s security service for complicity in their detention, rendition and torture in 2004 at the hands of the CIA on the Indian Ocean island of Diego Garcia, one of the agency’s global network of “dark sites.”

Detainees at these sites were subject to detention for years under the most inhumane conditions, torture, water boarding, sexual assault, sleep deprivation, forcing inmates to stand on broken limbs, and murder, for which no officials have stood trial.

While it was common knowledge that Diego Garcia was used as a US detention facility, the British government has always maintained that it never gave the US explicit permission to use the island for its rendition, detention and torture programme.

Balhaj claims that during his six years in a Libyan prison he was interrogated by US and British intelligence agents. His pregnant wife claims she was chained to a wall for five days, then taped to a stretcher for the 17-hour flight to Libya where she was detained in prison until just before the delivery of her son, who was born weighing just four pounds.

In 2012, the British government paid out £2.2 million to another Libyan dissident, Sami al-Saadi and his family, who stated under oath that the British intelligence authorities forcibly transferred them to Libya to be detained and tortured. This was to prevent the Libyans’ evidence being heard in court, and the foreign secretary and senior intelligence officials having to give evidence.

Belhaj has been determined to get the British government to admit to its crimes. He offered to call off the proceedings in exchange for just £3 in damages, an admission of liability for what was done to him and his wife, and an apology from the British government. The government rejected the offer and has since sought to get the courts to block the case.

Belhaj’s lawyers have cited documents found in abandoned government offices in Tripoli after the 2011 NATO-led invasion of Libya to topple the Gaddafi regime and install a puppet government. In the 2011 operation, NATO backed the same Al Qaeda-linked Islamist forces, the Libyan Islamic Fighting Group, of which Belhaj was a leader, and whose members NATO had earlier illegally rendered to Libya.

The documents include a letter from MI6’s senior officer, Sir Mark Allen, to Libya’s intelligence chief, Musa Kusa, showing that the CIA, with help from British intelligence, used Diego Garcia as a stopover for rendering Belhaj and his pregnant wife to be tortured in Libya.

Last November, the government went to the UK’s Supreme Court in an effort to block the case, arguing that British courts cannot hear Belhaj’s case since agents of foreign intelligence agencies, meaning the CIA, were also involved in the operation. The government has thus far spent at least £10 million trying to prevent the case from being heard. The court has yet to deliver its judgement on whether Belhaj’s suit can proceed.

Another case is being brought by 12 opponents of the Gaddafi regime—six Libyan men, the widow of a seventh, and five British citizens of Libyan and Somali origin—against both Britain’s spy agencies, MI5 and MI6, the Home Office and the Foreign Office.

Using evidence from the recovered documents, they are alleging false imprisonment, blackmail, misfeasance in public office and conspiracy to assault, and demanding damages. They claim that the British government worked closely with Libya and used information obtained under torture from Sami al-Saadi and Abdel Hakim Belhaj as evidence against them during partially secret proceedings in London.

Initially, both Straw, who as foreign secretary in Prime Minister Tony Blair’s Labour government was responsible for MI6, and Allen denied any British involvement in extraordinary rendition. Successive British governments have sought to cover up what was going on. When the Libyan documents revealing British complicity in detentions and torture came to light, Straw claimed he could not be expected to know everything the intelligence agencies were doing.

The intelligence services have flatly contradicted this, saying that it was “ministerially authorised government policy.” Sir Richard Dearlove, head of MI6 at the time, said, “It was a political decision, having very significantly disarmed Libya, for the government to cooperate with Libya on Islamist terrorism.”

In 2011, the NATO-led invasion of Libya to topple the Gaddafi regime, which the Blair government had previously brought in from the cold in 2004, was to use these same “Islamist terrorists” as its proxies.

According to the Guardian, Eliza Manningham-Buller, who headed the domestic intelligence service MI5, was furious about MI6’s involvement in extraordinary rendition and torture. She wrote to Blair complaining about it, saying its actions may have compromised the security and safety of MI5 officers and their informants, and even threw MI6 staff out of MI5’s headquarters. Human rights lawyers are now demanding that the government publish the letter.

Following the publication of the correspondence in 2011, the London Metropolitan Police carried out a four-year investigation, gathering 28,000 pages of evidence about Britain’s role in extraordinary renditions and torture, which it presented to the Crown Prosecution Service.

The CPS claimed that there was insufficient evidence to charge anyone. However, it was forced to acknowledge that “the suspect,” described as a public official, meaning Sir Mark Allen, knew about the renditions of the Belhaj and Saadi families, thereby blowing apart the government’s attempts to keep its criminal role in renditions and torture under wraps.

Crucially, in an attempt to protect Straw, the CPS did not invoke section 7 of the 1994 Intelligence Services Act that protects MI6 officers from prosecution for illegal acts anywhere in the world as long as the secretary of state had authorised their actions in writing.

The lawyers for the Belhaj and Saadi families have said they intend to challenge the CPS’s decision not to bring charges. If their challenge fails, they could initiate judicial review of the decision-making process.

Straw’s criminality was also highlighted in the Chilcot inquiry into the Iraq war. According to its report, he played a key role in “hardening up” a document setting out the threat supposedly posed by Iraq and its non-existent weapons of mass destruction under Saddam Hussein.

This is not the first time such a claim was made. The 2004 Hutton inquiry revealed an email written by Straw’s then private secretary that described his role as foreign secretary in “hardening up” the dossier with a “killer paragraph.”