The Government insisted it is "regularly" raising its concerns about the condition of Guantanamo Bay inmates with the US.
Trade minister Ian McCartney gave the assurance during a late-night Commons debate about Bisher al-Rawi, an Iraqi citizen who became a UK resident in the Eighties and who has been held without charge at the detention camp for four years.
The Argus has campaigned for the release of fellow detainee and former Brighton resident Omar Deghayes, who has also been held for more than four years.
The Government insists it has no power to intervene on behalf of the nine British residents believed to be among about 400 terror suspects still held at Guantanamo.
A legal bid to force the Government to demand the return of Mr al-Rawi and Mr Deghayes failed last October.
Appeal-court judges rejected arguments that the foreign nationals should be treated as UK citizens.
Mr McCartney told MPs the Government's position on the detention centre was clear.
He said: "We believe Guantanamo should close. We regularly raise humanitarian concerns about detentions at the Bay with the US, including those about detainees who were formerly resident in the UK."
This week a series of demonstrations will mark the fifth anniversary of the arrival of the first detainees at Guantanamo.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article