A defence minister has been sacked by Boris Johnson following a row over the government’s treatment of troops.

Johnny Mercer, the veterans minister, said he was sorry to have been “relieved of my responsibilities”.

It has been reported that he was on the brink of resignation over the government’s handling of historic prosecution of soldiers.

No 10 confirmed last night he had left government.

A Downing Street spokesperson said the prime minister had accepted his resignation and “thanks Johnny Mercer for his service as a… minister since 2019”.

At the same time Mr Mercer tweeted: “I’m sorry to have been relieved of my responsibilities in government tonight.”

In a stinging letter to the prime minister, also posted on his Twitter account, Mr Mercer said it was “with a heavy heart that I am forced to offer you my resignation from your government.”

He said that he had hoped that when Mr Johnson became prime minister a year and a half ago that would “signal a step change in veterans affairs in the UK”.

He added: “Whilst we continue to say all the right things, you will understand that if we fail to match that with what we deliver, we risk damaging an already bruised veterans cohort further, as I told you last month in our first face to face meeting, we crossed that line some time ago.”

Mr Mercer left government just hours after ministers announced they would exempt genocide and torture from controversial new legal safeguards for British troops serving overseas.

The Ministry of Defence (MoD) said the government would table its own amendment to the Overseas Operations Bill when it returns to the Commons tomorrow.

Last week the House of Lords voted by 333 to 228 to support a change to the Bill to ensure the most serious offences were not covered. The legislation is designed to protect service personnel from vexatious battlefield claims.

It will introduce a statutory presumption against prosecution five years or more after an incident.

The row which led to Mr Mercer’s departure was prompted in part by a number of prosecutions of soldiers who served in Northern Ireland during the Troubles.

In his letter to Mr Johnson, Mr Mercer promised to continue his campaign on behalf of those who served in Northern Ireland from the backbenches.