Hundreds of British soldiers who served in Iraq have received letters questioning their involvement in the alleged murder and abuse of prisoners during the Iraq conflict.

About 280 veterans have been sent letters notifying them of incidents currently under investigation by the government-established Iraq Historical Allegations Team (Ihat) and requesting they give evidence.

Some of the letters were hand-delivered by investigators, a move critics have branded as a "witch-hunt".

An Ihat spokeswoman, though, said the move was "standard police practice".

"Sometimes the letters are delivered by hand and it may be that if a potential witness is at home then the investigator will take the opportunity to ask a few questions," she said.

Ihat has referred cases of 35 alleged killings to the Service Prosecuting Authority (SPA), the military equivalent of the Crown Prosecution Service.

The SPA is also examining 26 cases of alleges mistreatment of detainees.

That number is expected to grow - the SPA said it is preparing to advise on an additional 20 cases of unlawful killing and 71 cases of mistreatment in the near future.

Andrew Cayley QC, the director of the SPA, said his team "will not flinch" from prosecuting British soldiers, but said the cases would be thoroughly examined and pursued only where there was evidence of wrongdoing.

The multimillion-pound inquiry's workload extended to 1,515 possible victims by September, of whom 280 are alleged to have been unlawfully killed.

Ihat's budget is set at £57.2 million, which runs until the end of 2019, a full 16 years after the start of the 2003 invasion.

UK forces withdrew from Iraq in 2009.