MPs have joined the calls for the US authorities to release the last remaining British detainee at Guantanamo Bay.
Mr Aamer has been held without charge for 13 years after he was accused of being a close associate of Osama bin Laden, something he denies.
MPs want Aamer - who was born in Saudi Arabia, lived in America and was granted leave to remain in the UK in 1996 - to be returned to his wife and four children in Battersea, London, urgently due to his deteriorating health.
ITV News correspondent Paul Davies reports from Westminster:
A number of senior MPs, including former ministers David Davis and Andrew Mitchell voiced their concerns over Mr Aamer's continuing detention during the debate in the House of Commons.
Mr Davis said that Britain and the US's handling of detainees at the notorious detention centre, was increasing the risk of terrorism and added that the standards for which millions died to protect in the 20th century have been betrayed since the 9/11 terror attacks.
"We are betraying the standards which millions died to protect in the last century and two world wars, and we are actually increasing the risk of terrorism because this legitimises the sort of barbarous behaviour we've seen too much of in the last few years," he told MPs.
Conservative former cabinet minister Andrew Mitchell said: "Justice is colour blind, it is creed blind, it should apply to everyone - universal justice - and it is not applying to Shaker Aamer and it is up to the House of Commons to give voice to this view.
"And the House of Commons must stand up today for justice of all citizens, wherever they are from, and never more so in this particular debate."
Earlier Mr Davis asked for the Government to outline the reason given by the US for not releasing Mr Aamer.
The former shadow home secretary said: "If it is that he will embarrass them then that is again a doubling up of the guilt on their part.
"Because frankly this is going to come out into the open at some point."
Foreign and Commonwealth Office minister Tobias Ellwood said he had spoken at length with the US embassy today on the matter.
He said: "The UK Government is committed to bringing Mr Aamer back to the UK and we have made our position very very clear to the US Government. We want him released as a matter of urgency and we know that they fully understand this request."
The Commons debate was held after an Amnesty petition with more than 32,000 signatures demanding the release of Mr Aamer was delivered to Downing Street.