Today’s case was described as ‘ludicrous’ by defence minister Penny Mordaunt (pictured

British soldiers face a new wave of legal claims – this time from hundreds of suspected Taliban insurgents who say they were held for too long by UK forces.

Fanatics believed to be intent on killing and maiming British troops with roadside bombs are set to legitimately argue they should not have been detained for longer than 96 hours.

Their success depends on the outcome of a Supreme Court case concerning a convicted insurgent, Serdar Mohammed, which starts today. Effectively, he is suing Britain for not shooting him in a firefight and taking him into custody instead, according to a defence minister.

If he wins, around 80 Afghans – who are represented by controversial law firm Leigh Day and have already lodged claims – stand to receive tens of thousands of pounds.

Immediately afterwards, hundreds more claims are expected to flood into the Ministry of Defence and millions of taxpayers’ money will have to be paid out.

It has sparked fears that troops who served in Afghanistan will be hounded in the same way as those who fought in Iraq as ‘ambulance-chasing’ law firms pursue the claims.

Today’s case – described as ‘ludicrous’ by defence minister Penny Mordaunt – involves Mohammed, an Afghan gunman suspected of being a senior Taliban commander involved in the large-scale production of roadside bombs used to blow up British troops.

He was later convicted for being an insurgent – but his lawyers argue that he was detained unlawfully.

His case – brought under the Human Rights Act – is the first to challenge the legal basis for UK detention operations in Afghanistan. Under Nato guidelines, suspects held there by international forces could only be detained for a maximum of 96 hours.

After this they should have been released or handed to Afghan officials. Miss Mordaunt has said of the case: ‘When the courts entertain claims against our forces such as the case of an insurgent bomb maker suing us for not shooting him in a firefight, but instead taking him prisoner and holding him until we could guarantee he would not face mistreatment in the local justice system, then it is not just our Armed Forces who suffer, the cause of human rights suffers too. The notion that dangerous insurgents cannot be detained for more than a few hours is ludicrous.

Armed Forces Minister Penny Mordaunt adjusts her helmet before watching a live firing exercise by members of the Infantry Battle School at the Sennybridge

‘Our forces must be able to detain enemies who attempt to maim and kill UK service personnel and civilians. If the law does not allow that then the law must change.’

It can also be revealed that on top of the compensation cases, a team of British detectives is looking into claims that UK troops murdered, maimed and ill-treated suspected Taliban insurgents.

They are investigating 604 claims as part of a criminal probe – similar to the Iraq Historical Allegations Team – into incidents during the 13-year war. The claims are believed to include 52 deaths. British soldiers will be questioned about their role on the battlefield and could face murder charges.

Last night Colonel Richard Kemp, who commanded British forces in Afghanistan, said Britain must put a stop to this persecution of soldiers

The Royal Military Police are conducting the investigation, codenamed Operation Northmoor.

It involves claims of mistreatment by 144 Afghans who were believed to have helped kill and maim UK troops. Police have completed investigations into 68 complaints by 21 Afghans. No cases have been referred to the Service Prosecution Authority.

The taxpayer’s bill for Afghanistan cases is expected to be higher than the one for Iraq, which currently stands at £100million. A total of £5.3million has so far been paid out in compensation to Afghans.

Last night Colonel Richard Kemp, who commanded British forces in Afghanistan, said: ‘Unless the Government puts a stop to this, the same lawyers mounting Iraqi claims will continue to do the same trick in Afghanistan – only the war was much longer. The hounding of British soldiers will just go on and on and on. It needs to end.’

Leigh Day – which is under investigation for alleged unscrupulous practices – said it was acting for about 80 Afghans who said they were unlawfully detained or mistreated.

The outcome of these cases depends on the hearing at the Supreme Court, to which the MoD has appealed. Mohammed was held by UK forces in 2010 and convicted of being a Taliban member. He says he was unlawfully detained by being held by UK forces for 106 days.

A Leigh Day spokesman said: ‘Last July, the Court of Appeal unanimously held that UK is not able to detain individuals without due legal process, which it found was lacking in Mr Mohammed’s case.’