Tony Blair is to set up a new organisation to fight the forces he believes led to Brexit and the election of Donald Trump - but is likely to be snubbed by Theresa May.

No 10 suggested that the Prime Minister would be too "busy" to look at the institute's work.

Mr Blair said he had decided to act because he was worried about the world that his children and grandchildren will grow up in.

Read more: Chancellor Philip Hammond dashes Nicola Sturgeon's hope of bespoke Brexit deal for Scotland

The former Labour leader recently predicted that the UK's decision to leave the EU could be reversed.

He told Remain voters that they were " the insurgents now” and said that the UK should keep its "options open" on a possible second referendum.

Announcing the new group, Mr Blair ruled out making a return to frontline politics.

“I have made it abundantly clear that this is not possible, " he said.

"However, I care about my country and the world my children and grandchildren will grow up in; and want to play at least a small part in contributing to the debate about the future of both.”

Read more: Chancellor Philip Hammond dashes Nicola Sturgeon's hope of bespoke Brexit deal for Scotland

The new organisation will include his current programmes in Africa, the Middle East and on faith.

But another strand will look at the current challenges in global politics, including Brexit and the election of Mr Trump.

Mr Blair said that since leaving office in 2007 he had "learnt a huge amount about the world and frankly what I can do and can't do to affect it positively".

Part of the new organisations's focus would be "around the European debate; but this will not be its exclusive domain. It has to go far wider than that since in many ways the Europe debate is a lightning rod for the whole of politics."

Read more: Chancellor Philip Hammond dashes Nicola Sturgeon's hope of bespoke Brexit deal for Scotland

Asked if the Prime Minister would look at its work, Mrs May's official spokeswoman said: “The Prime Minister is pretty busy getting on with the job of leading the country and delivering on the will of the British people to leave the EU.”

Mr Blair reportedly met with the Liberal Democrat leader Tim Farron earlier this week, and has also had discussions with Nick Clegg and George Osborne in recent weeks.

Meanwhile, in an interview with the BBC's Newsnight Cherie Blair said that a centre-left party was “something worth fighting for”.

“Maybe I am just an internal optimist – a glass is always half-full, not half-empty," she said.

“I don’t think that we are going to see people turning their backs on the open-minded, tolerant society, that we are so proud of that we have here in Britain.”

She added: “This is something worth fighting for – there is no point feeling depressed about it. We have to assert that what is right and what is kind, and the good things that happen in our society.

“And, not allow those with loud voices who are often talking in these echo chambers that are the internet come around and try and pretend everybody thinks like them.”

Former Ukip leader Nigel Farage said of Mr Blair and Mr Farron: "I thought politically they were dead and yet like the Hammer House of Horror this arm is creeping out of the coffin (and) says perhaps we should have a second referendum and stay inside the European Union.”