Bradley Manning, the US soldier accused of leaking secret cables to the Wikileaks website, has been subjected to "cruel and unnecessary" treatment by US authorities, Labour MP Ann Clwyd has said.

Leading a short debate on 4 April 2011, Ms Clwyd, a former special envoy on human rights to Iraq, told MPs that Private Manning was being held in solitary confinement for 23 hours a day at the Marine Corps brig in Quantico, Virginia.

He had complained of being stripped at night, with guards asking him whether he is "okay" every five minutes, she told MPs.

She read from a statement issued through his lawyer: "'At night, if the guards cannot see me clearly, because I have a blanket over my head or I am curled up towards the wall, they will wake me in order to ensure that I am okay.'"

These conditions served "no purpose other than to humiliate and degrade Bradley Manning", Ms Clwyd concluded.

She warned that the soldier's treatment - and the UK's response to it - could undermine the "moral authority" needed to influence "countries where human rights are not so well observed".

Responding to the debate, Foreign Office Minister Henry Bellingham said British diplomats will express MPs' concerns with officials in Washington.

Mr Bellingham said that staff at the British embassy in Washington had already discussed Bradley Manning's detention with the US State Department once.

But he emphasised that President Barack Obama had "sought and received assurances from the Department of Defence that Private Manning's treatment is 'appropriate' and meets US 'basic standards'."

The 23-year-old from Crescent, Oklahoma, has now been charged with aiding the enemy, a crime which can bring the death penalty or life imprisonment.