An armed police officer patrols near the Ministry of Defence in London. File/Reuters

An inquiry investigating allegations that British special forces carried out dozens of extra-judicial killings in Afghanistan a decade ago will begin hearing evidence in public on Monday.

Britain’s defence ministry ordered the independent inquiry last December after a BBC TV documentary reported that soldiers from the elite Special Air Service (SAS) had killed 54 people in suspicious circumstances.

It also came after two families, who accuse the SAS of killing their relatives in 2011 and 2012, began legal action to demand judicial reviews of their cases.

"Our clients hope that the opening of this inquiry marks the end of ‘the wall of silence’ and obstruction that has confronted them over the last decade," said Tessa Gregory from law firm Leigh Day which is representing families of 29 people who were killed.

"The bereaved families look to the inquiry to fearlessly uncover the truth of the deaths of their loved ones and to ensure that those responsible are held to account."

The chair Charles Haddon-Cave has said the inquiry would examine whether there was unlawful activity by British military personnel between mid-2010 and mid-2013 during 'deliberate detention operations', and whether there was credible information of extra-judicial killings.

It will also look at whether investigations by the military police were properly conducted, and if any unlawful killings were covered up to prevent them "ever coming to light".

Haddon-Cave said the allegations were "extremely serious".

British military police have previously conducted several inquiries into allegations of misconduct by forces in Afghanistan, including those made against the SAS, but the Ministry of Defence has said that none found enough evidence for prosecutions.

While the hearings will begin in public, some of the evidence relating to special forces will be restricted on national security grounds.

"In 2012, our house was raided by foreigners and my brother and sister-in-law were killed and their two children severely injured whilst they were sleeping in their bed," Mansour Aziz said in a statement released by Leigh Day.

"We want to know the truth and why it was our house that was raided. We are asking for the court to listen to these children and bring justice."

Reuters