But he had not been able to visit him due to Kennedy's deteriorating condition, broadcast reports said.

Obama called Kennedy the 'greatest United States senator of our time'. German Chancellor Angela Merkel and British Prime Minister Gordon Brown were among foreign leaders who praised Kennedy's conviction and commitment to peace.

The youngest Kennedy brother, also known as 'Teddy', was known as a liberal lion of the Senate, pushing causes dear to the Democratic Party but also known for working across the political aisle with Republicans.

'While we didn't see eye-to-eye on many political issues through the years, I always respected his steadfast public service,' former president George H.W. Bush said in a statement, calling Kennedy a 'seminal figure' in the Senate.

Ted followed his brothers in running for president after John F. Kennedy was gunned down while in office in 1963 and Robert Kennedy was also fatally shot in 1968 while campaigning for the presidency.

Edward Kennedy's aspirations for the White House, however, were hurt by a 1969 car accident in which he drove off a bridge at Chappaquiddick and his female passenger, Mary Jo Kopeckne, was killed. He ran for president once, in 1980, challenging incumbent

Jimmy Carter and losing in the Democratic Party primaries.

Kennedy then turned his attention back to his illustrious career in the Senate, playing major roles in passing legislation on health care, civil rights and education.

'The Kennedy family and the Senate family have together lost our patriarch,' said Senator Majority Leader Harry Reid.

'We've lost the irreplaceable centre of our family and joyous light in our lives, but the inspiration of his faith, optimism and perseverance will live on in our hearts forever,' the family statement said.

'We thank everyone who gave him care and support over this last year, and everyone who stood with him for so many years in his tireless march for progress toward justice.'