Sir Keir Starmer has appointed Jonathan Powell, Sir Tony Blair’s former chief of staff and background architect of the Good Friday Agreement, as national security adviser.

The veteran diplomat recently played a major role in talks over the Chagos Islands sovereignty dispute, which earlier this year saw Britain hand over the territory to Mauritius.

He will take over from Sir Tim Barrow in the No 10-based position after serving 17 years in the Foreign Office and a decade in Downing Street.

The Prime Minister said Mr Powell’s experience in helping to negotiate a peace deal in Northern Ireland and working on “some of the most complex conflicts in the world” meant he was “uniquely qualified” to advise the government on global challenges.

He is expected to play a key role in forging ties with the new US administration of Donald Trump, as well as helping to shape the UK’s response to the conflicts in Ukraine and the Middle East.

The AP news agency understands that Mr Powell was appointed as a special adviser in a political capacity – a break from the norm which saw previous post holders assumed as civil servants.

He is the chief executive of Inter Mediate, a UK charity working on international conflict resolution.

Mr Powell’s tenure as one of Sir Tony’s closest confidantes between 1997 and 2007 came under intense scrutiny during the Hutton Inquiry into the death of scientist David Kelly.

He found himself in the media spotlight after it was revealed he had asked a security chief to change parts of the notorious Iraq arms dossier because some of the language was a “bit of a problem” for Downing Street.

His return to Number 10 is part of a wider upheaval under the new Labor administration, which has seen former Blair-era figures brought back to the heart of government.

Last month, Claire Reynolds, a former adviser to Sir Tony and Gordon Brown, was appointed as Sir Keir’s political director, and several senior ministers also served in key roles during both of New Labour’s terms as prime minister.

“Jonathan has dedicated his career to protecting the interests of the country,” the prime minister said after the appointment.

“Combined with his experience of helping to negotiate the Belfast (Good Friday) Agreement and working on some of the world’s most complex conflicts, he is uniquely qualified to advise the Government on how to address future challenges and engage with counterparts around the globe to protect and advance. the interests of Great Britain.”

Thanking Sir Tim for his service during “some of the most difficult times in recent history”, the Prime Minister added: “He will no doubt continue to play a positive role in these issues in the future.”

There was speculation under the previous Conservative government that Sir Tim would move on to replace Ms Karen Pierce as Britain’s ambassador to the US, but she is expected to stay on.

Mr Powell said: “I am honored to have been appointed National Security Adviser (NSA) to the Prime Minister. This is an extremely important role at a time when national security, international relations and domestic politics are so interconnected.

“As the Prime Minister has stated, national security is at the heart of this country’s response to the many challenges we face, and having an integrated response will be crucial to our success. I look forward to advising the Prime Minister and working closely with ministers and officials in this new role.”

Despite Mr Powell’s experience, the decision to make a political appointment to the NSA post is unusual and has already been criticized by opposition critics.

Paymaster General Nick Thomas-Symonds has questioned Boris Johnson’s nomination of his ally Lord Frost for the role in 2020, on the grounds that the post holder should be “independent, impartial (and) specialist”.

“That is why a political appointment takes this government into such dangerous territory,” Mr Thomas-Symonds, the shadow home secretary, said at the time.

The Conservatives criticized the drafting of “another Labor apparatus” and pointed to earlier remarks made by Mr Powell on the Chagos Islands.

A Conservative Party spokesman said: “It is disappointing that the Government has appointed another Labor apparatchik to a senior role, leaving out an experienced general.

“Mr Powell’s previous comments about the unimportance of Britain’s overseas territories are extremely worrying and many will be concerned that more will follow.”

After the announcement of the British-Mauritian deal, which will see the UK retain jurisdiction over a strategically important air base on the island of Diego Garcia, Mr Powell dismissed concerns about relinquishing control of the archipelago.

He told Times Radio: “I don’t think we should worry too much about losing that territory. We’re probably losing more to tidal erosion on the East Coast (of England) than that.”

He also pointed out that negotiations over the territory had begun under the Tories, including James Cleverly, who he said had become “enthusiastically” involved in the process as foreign secretary, despite criticizing the deal last month.