Andy Burnham has approved £40 million in new aid funding for Caribbean countries, as he prepares to offer a 'formal apology' for Britain's historic role in the slave trade.

Diplomatic sources said the Prime Minister is ready to apologise for Britain's role in the slave trade within months, despite warnings it will trigger claims for trillions of pounds in compensation.

Mr Burnham was expected to discuss the offer on Monday night with Barbados PM Mia Mottley, who has led the campaign for the UK to pay 'reparations' for slavery.

Downing Street said it was 'right that a formal apology is discussed properly with the countries and communities most affected, rather than simply deciding unilaterally what form it should take'.

No 10 insisted that the PM would not agree to pay direct compensation for the UK's historic role.

But, during talks at the Commonwealth summit in Antigua this week, ministers will discuss potential help with debt restructuring and funding for tackling climate change. Future foreign aid could also be channelled into education and health programmes demanded by reparations campaigners.

On arrival in the paradise island on Monday night, Mr Burnham signed off £40 million to 'accelerate critical infrastructure investment in the Caribbean, including renewable energy'.

Although the funding is not directly linked to the slavery row, it will be seen as another sop to those campaigning for reparations.

A government source said the money would help deliver the PM's ambition to build a 'stronger relationship between the UK and the Caribbean nations to deliver opportunity on both sides of the Atlantic'.

Ms Mottley has previously suggested that Barbados alone is owed £3.2 trillion by slave trading nations for the crimes of the past.

Kemi Badenoch branded Mr Burnham the country's 'chief apologiser' at the weekend and said there was no case for asking British taxpayers to fund reparations.

Nigel Farage condemned Mr Burnham's decision to pander to the demands of 'very Left-wing Caribbean governments' who he said were 'trying it on' over slavery demands and ignoring Britain's leading role in ending the vile trade.

The Reform UK leader said the PM risked embarrassing the King, who is also under pressure over slavery at this week's Commonwealth Heads of Government summit in Antigua. He said the Monarch had been 'put in a very difficult position by our Prime Minister'.

Mr Burnham faced controversy at home on Monday after the private jet carrying the government delegation from London to the Caribbean was diverted to pick up him and his wife Marie-France van Heel from Manchester where they spent the weekend.

The detour is expected to cost the taxpayer up to £20,000, although No 10 declined to say exactly what the final bill to the public will be.

The PM's official spokesman said his travel arrangements were 'made on the basis of security, operational requirements, and value for money for the taxpayer'.

But Tory frontbencher Neil O'Brien accused Mr Burnham of hypocrisy, saying: 'He lectures and imposes massive green taxes on the rest of us but then uses a massive jet as the world's most expensive Uber.'

Mr Burnham has raised the prospect of an apology in a bid to prevent a repeat of the 2024 Commonwealth summit where Sir Keir Starmer was harangued by fellow leaders about slavery.

Speaking on arrival in Antigua, the PM said the Commonwealth had 'the potential to be a powerful force for good' if it focused on the future.

'Britain is bringing a new approach to this meeting as we look to reshape a new era for the Commonwealth, as well as being open to discussions about the past,' he said.

In a video posted on social media, Foreign Secretary Ed Miliband said a formal apology would be a 'significant step'.

Mr Miliband said financial reparations were not the 'right or feasible answer' to historic slavery, but suggested the Labour government could try to make amends in other ways.

He said ministers 'want to focus on meaningful, practical cooperation – which includes education and cultural exchange – and how we can work together on the mutual issues of climate resilience, development and economic opportunity.'