British troops are facing a fresh wave of criminal investigations into alleged abuse after the Ministry of Defence quietly set up a new inquiry into soldiers’ actions in Afghanistan, The Telegraph has learnt.

The allegations include those from a Taliban bombmaker who claims his arrest and detention for 106 days was illegal, despite troops’ belief that he would make bombs designed to kill British soldiers if they released him.

So far, criminal investigations into British soldiers have focused mainly upon their actions in Iraq. But new figures obtained by the Telegraph show that more than 550 historic allegations of war crimes in Afghanistan are now under investigation by a special police unit set up by ministers.

It means investigators are now examining claims of abuse in more than 2,200 cases in both Iraq and Afghanistan.