Boris Johnson and Dominic Raab have paid tribute to the victims of Srebrenica on the 25th anniversary of the massacre in Bosnia and Herzegovina.

The Prime Minister and Foreign Secretary issued statements to mark a quarter of a century since the genocide in which Bosnian Serb forces led by General Ratko Mladic killed 8,372 mostly Muslim men and boys.

It was the worst atrocity on European soil since the end of the Second World War.

Mr Johnson said in a video posted on Twitter: “I want to join with you once more in mourning the victims of those terrible events, and to stand with the families in their fight for justice.

“As in so many cases from this conflict which brought violence and destruction across the western Balkans, many families still do not know what happened to their loved ones. Many perpetrators have still not been held to account.

“And there are those who would prefer to forget or deny the enormity of what took place. We must not allow that to happen.

“We owe it to the victims and to future generations to remember Srebrenica and to ensure it never happens again.”

Mr Raab said in a statement: “On the 25th anniversary of the Srebrenica genocide, we remember the victims and the anguish of their families.

“During my time in the Hague between 2003 and 2006, pursuing those responsible for this dark chapter in European history, I was reminded daily of the heinous cruelty perpetrated against the innocent.

“The UK is determined to end impunity and help rebuild those countries affected – as our commitment to the ICC, and UK investment and support for Bosnia demonstrates.”

However, Mr Johnson is facing calls from 30 MPs to apologise for comments he made in the Spectator in 1997 regarding the genocide.

In a letter to the PM, the cross-party group led by Labour’s Tony Lloyd wrote: “In 1997, when you were a political columnist for the Spectator, you wrote an article challenging Bianca Jagger’s support for more direct intervention against the Serbian Army in the Bosnian war.

“You wrote: ‘Alright, I say, the fate of Srebrenica was appalling. But they weren’t exactly angels, these Muslims’.

“As we commemorate the 25th anniversary of the atrocity, it is unthinkable that you would publicly attend national memorial events, without having apologised for such comments.”

A Government spokeswoman said: “This quote is clearly taken out of context.

“The Prime Minister has, over the last 25 years, consistently condemned the Srebrenica genocide as one of the worst crimes in history.”