Veterans are being urged not to travel to Ukraine to fight, in a letter sent by a minister to military charities.

A small number of serving British personnel are believed to have gone absent without leave to join the resistance against the Russian invasion, while veterans and Britons without combat experience have also travelled to Ukraine.

Defence Secretary Ben Wallace has already warned that those travelling to the conflict zone would not be there for “a selfie and six weeks” but would be in the war “for real”.

In an attempt to drive home that message, veterans minister Leo Docherty has written to armed forces charities to encourage those tempted to travel to the warzone to instead turn their efforts to helping the Ukrainian people from the UK.

The Ministry of Defence (MoD) said Mr Docherty used his letter to press home that the Government does not support volunteers going to fight.

Officials said he also warned veterans that those travelling to spar with Russian troops “will put themselves at significant risk by entering into a conflict area”.

Mr Docherty said: “We know that Russia’s illegal invasion has rightly brought out strong feelings of support for the Ukrainian people.

“Veterans always step up in times of need, but they must channel their skills, experience and passion into legal routes of support for Ukraine and not engage in the conflict.

“There are many ways that we all can support the people of Ukraine, including through donating money to charity.”

There had initially been confusion on the Government’s position after Foreign Secretary Liz Truss, in comments during an interview to the BBC on February 26, said she would “absolutely” support UK nationals who chose to battle for Ukraine.

However, she rowed back from those comments during a press conference in the US on Wednesday, insisting she had been “expressing support for the Ukrainian cause” in her comments, and that there are “better ways” to contribute to the Kyiv defence.

Meanwhile, some veterans have reportedly received cold call approaches from private militia groups inviting them to join the fighting in Ukraine.

The BBC reported the militia groups had been scouring social media to recruit ex-soldiers.

In his letter, Mr Docherty offered to support charities, via the Office for Veterans’ Affairs and the MoD, should they become aware of veterans looking to travel to Ukraine.

Veterans who find their health and wellbeing affected by the war can seek specialist support from health services, such as NHS Op Courage in England, and the Veterans’ Gateway, the department said.

Officials pointed out that the veteran community can donate to charities providing humanitarian relief in Ukraine, with the UK Government having matched pound-for-pound £25 million of public donations to the Disasters Emergency Committee (DEC) Ukraine Appeal.