Senator Edward Kennedy, the liberal champion of the US Senate who carried on the political legacy of his slain brothers, was buried on Saturday after four days of emotional tributes.

The man who President Barack Obama called the 'greatest legislator of our time' received final sendoffs in Boston and Washington, cities where the Irish-American patriarch of America's pre-eminent political family wielded his power.

After a funeral Mass in Boston where the US political elite packed a Roman Catholic church, Kennedy's flag-draped coffin was flown to Washington, where thousands lined the streets to see his motorcade make its way to Arlington National Cemetery.

Two hundred invited guests gathered around his gravesite for final readings as darkness fell. He was buried near the graves of President John F Kennedy, assassinated in 1963, and Senator Robert Kennedy, who was killed while campaigning for president in 1968. A military honour guard gave a three-volley rifle salute in honor of the Democratic senator.

Cardinal Theodore McCarrick, a friend of Kennedy's, presided at the burial and read from a letter to Pope Benedict in which the senator wrote: 'I am writing with deep humility to ask that you pray for me as my own health declines ... I know that I have been an imperfect human being but with the help of my faith, I have tried to right my path.'    

McCarrick also read the response from the Vatican which said the Pope gave Kennedy his 'apostolic blessing.'    

Since Kennedy died on Tuesday of brain cancer at age 77, there have been a series of memorials for the last of the Kennedy brothers, showing the fascination many Americans have for a family that is the closest thing to US royalty.

Victoria, his second wife who is credited with turning around Kennedy's life after their 1992 marriage, was at the center of the tributes, which match what the United States would normally reserve for a former president.

Before going to the cemetery, the motorcade stopped for a brief prayer service outside the US Capitol, where lawmakers from both political parties, staffers from his 47 years in the Senate and a crowd of hundreds sang patriotic songs.

Family members waved through open car windows as the motorcade slowly traced the same route that Kennedy's slain brothers took before him to Arlington, a cemetery reserved for military and prominent Americans.

In his euology in Boston, Obama recalled the many tragedies Kennedy lived through, calling them 'a string of events that would have broken a lesser man.'    
'Ted Kennedy's life's work was not to champion those with wealth or power or special connections. It was to give a voice to those who were not heard,' Obama said.

In Kennedy, who Obama called the 'soul of the Democratic Party,' the president lost an ally in his uphill battle to overhaul the  $2.5 trillion US healthcare system in which nearly 46 million people go uninsured. There were numerous reference during the services to what Kennedy had said was 'the cause of my life.'    

Kennedy, a senator under 10 presidents, could charm Republicans into backroom deals even while conservatives ridiculed him as a hopeless lover of big government.

Police said 50,000 people came to a two-day public viewing of his casket at the John F Kennedy Library and Museum.

'Where would I be as a black man without the Kennedys?' said Clint Haymon, one of hundreds of mourners gathered outside the church in pouring rain. 'They believe in civil rights and that's why I am here to honor this great man.'    

Loved by liberals, Kennedy was both respected and reviled by conservatives, many of whom never forgave him for the Chappaquiddick car a