Image caption Mr Blair was awarded the US Congressional Gold Medal in 2003

Former Prime Minister Tony Blair has been awarded one of the highest private honours in the US for his role in the Northern Ireland peace process.

Mr Blair was given the Liberty Medal by the National Constitution Center in Philadelphia.

The award comes as Mr Blair has cancelled promotional events for a new autobiography amid protests by critics of his role in the US-led Iraq war.

Officials with the centre acknowledge Mr Blair is a contentious choice.

The Liberty Medal was awarded to Mr Blair on Monday evening by former US President Bill Clinton.

Accepting the medal, Mr Blair said: "Liberty is not acquired by accident. It's won by endeavour."

He added that he wanted to strive for a world "in which people are free to follow their religion without fear or favour, and respect those of a different faith than themselves".

'Contentious choice'

Mr Blair - who was UK prime minister between 1997 and 2007 - has already been awarded the Congressional Gold Medal by the US government.

Selected Previous winners 2009 - Film director Steven Spielberg

2008 - Former Soviet Premier Mikhail Gorbachev

2007 - Singer and campaigner Bono

2006 - Former US Presidents George HW Bush and Bill Clinton

2005 - Ukrainian leader Viktor Yushchenko

2004 - Afghan President Hamid Karzai

2003 - US Supreme Court Justice Sandra Day O'Connor

2001 - UN Secretary General Kofi Annan

1999 - South Korean Leader Kim Dae-jung

1996 - Jordan's King Hussein and Israeli PM Shimon Peres

He is currently serving as envoy for the international Quartet of Middle East peace mediators, the US, UK, EU and Russia.

The National Constitution Center is an independent, non-profit organisation that promotes understanding of the US constitution and its relevance. Recipients of the Liberty Medal receive $100,000 (£65,000).

"There is always an element of controversy when you pick people at the forefront of change," said president David Eisner.

"They are usually very controversial figures. We understand… how differently Tony Blair appears to be viewed by many people in the UK as compared with many people in the US."

On tour to promote his new book, Mr Blair has attracted hostile protests from British and Irish anti-war protesters angered at his role in supporting the US-led war in Iraq.

Past US honourees include Thurgood Marshall, the first black Supreme Court justice, and former US presidents Jimmy Carter, George Bush Sr and Bill Clinton.

There have also been more eclectic recipients in director Steven Spielberg, singer Bono and DNA pioneers James Watson and Francis Crick.