Abdel Hakim Belhadj says he is taking legal action following allegations the former foreign secretary personally permitted his illegal rendition.
Lawyers representing Abdel Hakim Belhadj confirmed legal papers had been served on the Labour MP after reports suggested Mr Straw had signed documents that allowed the rebel to be sent back to his homeland in 2004.
The civil action, which is against Mr Straw personally, seeks to examine his exact role in the rendition and claim damages from him for the trauma involved.
Mr Straw has previously denied any involvement in ‘extraordinary rendition’ (the abduction and illegal transfer of a person from one nation to another). He declined to comment to reporters on Wednesday because legal proceedings were active.
Mr Belhadj’s lawyers, Leigh Day & Co, said they sent the MP a letter yesterday asking him to produce a number of documents.
Mr Belhaj and his former co-detainee Sami al-Saadi have already said they will sue the former director of counter-terrorism at MI6, Sir Mark Allen.
Sami al-Saadi's story: read an extract from International Editor Lindsey Hilsum's book
Belhadj claims that he was rendered to Libya by the US authorities via Bangkok, and was imprisoned for six years in some of the country’s worst jails, including Abu Salim in Tripoli.
He claims that whilst imprisoned, he was interrogated by British agents.
Sapna Malik, a partner at Leigh Day & Co, said: “We have said all along that liability must follow the chain of command. These latest revelations bring us closer to that goal.”
In the civil court Mr Belhadj, Mr al-Saadi and their families are not only suing Mr Straw personally but also the Foreign Office, MI6 and the former MI6 agent Mark Allen.
In addition the Metropolitan Police is investigating MI6 agents and government ministers to see if they have committed a crime.
Thirdly Mr Belhadj is suing the Commissioner for the British Indian Ocean Territory because documents suggest he was rendered through the US military base on the British territory of Diego Garcia.
Documents found last August in the abandoned intelligence headquarters in Tripoli revealed close cooperation between the CIA, MI6 and Colonel Gaddafi’s secret service.
On 13 December 2005 Mr Straw told the Foreign Affairs Committee: “There simply is no truth in the claims that the United Kingdom has been involved in rendition, full stop. Because we haven’t been.”
But despite repeated denials that Britain’s Labour government was ever involved in extraordinary rendition, Mr Straw may yet have to state his case in court.
Read more from Channel 4 News: Met to probe Libyan rendition claims