Tony Blair is due to discuss the deportation of terrorist suspects with the President of Algeria, Abdelaziz Bouteflika, during his visit to the UK.
Bouteflika is the first Algerian head of state to visit Britain since 1962
Last month two men were sent back to Algeria on the grounds that they were a threat to national security.
The BBC has learned that the men have been released from custody and have been reunited with their families.
Britain is seeking assurances over the treatment of deportees, amid concern that they could be ill-treated.
The two suspects were among seven Algerians arrested last September following the 7 July attacks in London.
The pair, known as V and I, were deported on 16 and 17 June after they decided to give up their appeal against extradition.
They were held for five or six days at an undisclosed location but were then freed and reunited with their families. Neither has provided further details of their treatment.
Some 27 individuals currently await deportation on national security grounds and the largest group is Algerian.
But the process of removing them is stalled while the courts decide whether the possibility of ill-treatment is too great.
A new report from Amnesty International claims that torture does occur but the British government is currently trying to negotiate assurances that any deportees will be fairly treated.
This is likely to be discussed by the Prime Minister and President Bouteflika.
Although an agreement would make the possibility of deporting the remaining Algerians more likely, the final decision would rest with the courts.