Mr Mohamed returned to the UK after allegations were dropped
The government has come under renewed pressure to disclose what it knew about a UK resident who says he was tortured.
It has emerged that an MI5 officer visited Morocco three times while Binyam Mohammed says he was being tortured there as a terrorist suspect.
The government insists it did not know he was held in Morocco and Afghanistan before being taken to Guantanamo Bay.
Ex-shadow home secretary David Davis said the "likelihood" of UK complicity in torture had to be investigated.
Mr Mohamed is bringing a test case claims against UK authorities which, he says, were complicit in his alleged torture.
MI5 says its official did not know Mr Mohamed was in Morocco at the time.
The details emerged in a High Court judgement on Friday, which was an update on a ruling on the secret evidence in Mr Mohamed's case, originally made last year.
The government has already asked the police to investigate Mr Mohamed's claims - and denies categorically that the security services collude with torturers in any way
Lord Justice Thomas and Mr Justice Lloyd Jones took the unusual step of reissuing the judgement to include new material about the security services dealings with the case.
It emerged that "Witness B" - an MI5 official who had questioned Mr Mohamed previously when he was arrested in Pakistan in 2002 - had made three visits to Morocco, during the period Mr Mohamed said he was being held and tortured there.
The judgement says it was clear to the security service that by September 2002 he was being held in a covert location and they continued to supply information and questions.
But the judges said they were "unable to determine the significance (if any) of the visits of the MI5 official, known only as "Witness B".
BBC home affairs correspondent Andy Tighe said MI5 maintained its official did not know Mr Mohamed was in Morocco at the time and the two men did not meet.
But our correspondent added that MPs of all parties were now calling for the government to give a fuller account of Britain's involvement in his detention.
The chairman of the House of Commons Home Affairs Select Committee, Keith Vaz, told Channel 4 News that the revelations "require an explanation from either the attorney general or the home secretary".
Mr Davis said: "Every single new piece of evidence that comes out shows more and more likelihood of UK complicity in torture.
"Every single piece of evidence says more and more loudly we need to have a judicial inquiry. We cannot go on like this."
Shami Chakribarti, director of civil liberties pressure group Liberty, said she did not believe a police investigation would "get to the bottom" of the affair.
She added: "I now think that the time has come for the government to say we accept the need for an independent judicial inquiry, with special counsel who can investigate and delve into the heart of the secret state."
But legal charity Reprieve described it as a "strange coincidence".
Reprieve director Clive Stafford Smith said it was clear senior UK intelligence personnel had known about Mr Mohamed's treatment, adding: "It's clear that something incredibly fishy was going on down in Morocco.
"I would be immensely surprised if the British didn't know what was going on to Binyam, that he was being tortured in Morocco at the time."
Mr Mohamed had been accused of attending terrorist training camps and being involved a plot to set off a radiological device but the US authorities eventually dropped the allegations and released him from Guantanamo Bay.
The Ethiopian national, who moved to the UK when he was 15, returned in February and is among several former detainees taking legal action against the British authorities.
He says he was tortured after being arrested in Pakistan in 2002 and being moved to Morocco and Afghanistan, before arriving in Guantanamo Bay in 2004.
He accuses the UK authorities of being "complicit" in it and British intelligence of supplying some questions.
But the government has said it did not know his whereabouts between his arrest in Pakistan and his arrival in Guantanamo Bay.
In a statement, the Home Office said it would not comment on individual cases but "security service officers act within the law".
"The government unreservedly condemns the use of torture as a matter of fundamental principle and works hard with its international partners to eradicate this abhorrent practice worldwide," it said.
"The security and intelligence agencies do not participate in, solicit, encourage or condone the use of torture or inhumane or degrading treatment.
"For reasons both ethical and legal, their policy is not to carry out any action which they know would result in torture or inhuman or degrading treatment."
The High Court is also considering whether a summary of US reports on Mr Mohamed's detention should be published.
He believes it will prove the UK knew he was being tortured in Morocco before being flown to the US detention camp.
But Foreign Secretary David Miliband argues confidentiality is key to intelligence sharing and as it was US information, it was for them to decide when to publish it.
The US denies that evidence used against Mr Mohamed was obtained by torture while the UK government says it has never "condoned the use of torture".
In March, Attorney General Baroness Scotland confirmed the police would investigate whether an MI5 officer had been complicit in the alleged torture of Mr Mohamed.