The Service Prosecuting Authority director Andrew Cayley told BBC radio that it was "quite possible" that none of the original allegations will lead to a prosecution.

Cayley did not provide details of the allegation in the last remaining case.

British combat troops fought alongside other coalition forces in an effort to quell an Islamic insurgency that followed the 2003 US invasion and subsequent fall and execution of dictator Saddam Hussein.

Former lawyer Phil Shiner and a team in Berlin drew on the accounts of more than 400 Iraqis who allegedly witnessed or experienced crimes ranging from rape and torture to mock executions and other atrocities.

A UK tribunal struck off Shiner after finding him guilty of misconduct and dishonesty in connection with the allegations in 2017.

Cayley told the BBC that it was likely that no action would be taken in a separate International Criminal Court (ICC) probe.

"My sense is these matters are coming to a conclusion," he said.

A lawyer representing some of the soldiers accused by Shiner called for a public apology over the "vile war crime slurs".

"At long last, this witch hunt is coming to an end," lawyer Hilary Meredith said.

The UK Defence Ministry said in 2012 that it had paid pound15.1 million ($19 million, 17 million euros) to more than 200 Iraqis who had accused British troops of illegal detention and torture.