BELFAST (Reuters) - Britain's new government said on Wednesday it would scrap an amnesty scheme for ex-soldiers and militants involved in decades of violence in Northern Ireland that has been opposed by all major parties in the region and by the Irish government.

The move fulfils a promise in the Labour Party's election manifesto to repeal and replace the Legacy Act, which the government said "denies justice to the families and victims of the Troubles".

Specifically, it will repeal the "conditional immunity scheme," which has been found by the Northern Ireland High Court to be incompatible with Britain's obligations under the European Convention on Human Rights. It will also reverse the policy of prohibiting victims and families from bringing civil claims.

Victims' families, human rights organisations and both British unionist and Irish nationalist political parties have opposed the act, which has been subject to more than 20 legal challenges in Northern Ireland.

The outgoing Conservative government had defended the law by saying that prosecutions linked to the events of up to 55 years ago were increasingly unlikely and that the bill could help draw a line under the conflict.

The announcement comes ahead of a meeting between British Prime Minister Keir Starmer and his Irish counterpart Simon Harris at the British government's Chequers country residence later on Wednesday.

Harris, who took office in April has called for a "great reset" of ties with Britain, which have been fractious in recent years. His government had been challenging the Legacy Act at the European Court of Human Rights.

Around 3,600 people died in three decades of confrontation between Irish nationalist militants seeking a united Ireland, pro-British "loyalist" paramilitaries and the British military before a 1998 peace deal largely ended the conflict, known locally as the "Troubles".

(Writing by Conor Humphries)