There are fresh calls for the release of the last remaining British detainee at Guantanamo Bay following news he has been diagnosed with post-traumatic stress disorder and is "falling apart".

Shaker Aamer has been held at the detention camp in Cuba for 12 years without charge, despite twice being cleared for release.

Aamer's lawyers have now filed an urgent motion to the US courts seeking an immediate release on the ground of ill health. An independent medical report carried out on Aamer declared he is suffering from 11 mental and physical issues, including PTSD and debilitating headaches.

Dr Emily Keram, who assessed Aamer on behalf of legal rights charity Reprieve, said he is also suffering from a severe case of edema, which if left untreated may develop into an "underlying life-threatening organ or vascular dysfunction".

Kerma added: "Mr Aamer requires psychiatric treatment, as well as reintegration into his family and society and minimisation of his re-exposure to trauma and reminders of trauma."

Clive Stafford Smith, one of Aamer's lawyers, has now filed a motion in a Washington court and has sent a copy of his medial report to the foreign secretary William Hague.

Smith said: "This desperate news about Shaker's mental and physical state comes on top of twelve years of abuse, and it's hardly surprising to learn from an independent doctor that he is suffering severe PTSD in Guantanamo.

"Shaker has described himself as a rusty old car that is falling apart. There is no reason he should not have come home to his wife and kids when he was cleared, seven years ago. How is it that anyone in his right mind can think that a torture victim should suffer even one more day of abuse?"

Soon after the 9/11 attacks in 2001, Aamer was detained in Afghanistan accused of fighting at Tora Bora, a military engagement that took place at the beginning of the War on Terror.

He was transferred to Guantanamo in 2002 after spending time in Bagram Airfield, a US military base in Afghanistan.

He has remained a detainee at Guantanamo despite being cleared for release by both the Bush administration in 2007, and again by the Obama administration in 2009.

He denies being involved in terrorist activity and says he was in Afghanistan to conduct charity work.