Senator Edward Kennedy, JFK Jnr's uncle and head of the Kennedy clan, delivered the eulogy, which was heard by President Clinton, his wife Hillary, and their daughter Chelsea.

As the Clintons left Washington, flying to join family members at the Church of St Thomas More in Manhattan, the flag above the White House was lowered to half-mast as a mark of respect.

Mr Kennedy, his wife Carolyn Bessette Kennedy, and her sister Lauren Bessette died last week when their light aircraft crashed into the ocean south of Massachusetts.

'Every gift but length of years'

Senator Ted Kennedy read the eulogy for his nephew

Senator Kennedy told the mourners: "He and his bride have gone to be with his mother and father, where there will never be an end to love."

"We dared to think ... that this John Kennedy would live to comb grey hair with his beloved Carolyn by his side. But like his father, he had every gift but length of years," he said.

"He was part of a legend, and he learned to live with it."

Senator Kennedy delivered the eulogies at the funeral of his brother Robert in 1968 - the victim of assassination - and the funeral of JFK's widow, Jackie Kennedy Onassis, who died of cancer in 1994.

Boxer Muhammed Ali was among celebrities and politicians to attend

Some 350 people in total were thought to have attended the private service at the church where JFK Jnr's mother Jackie was a regular worshipper.

The service was conducted by Rev Charles O'Byrne, who also presided over the ceremony on Thursday in which the ashes of the three victims were scattered at sea.

Rev O'Byrne also conducted Mr Kennedy's wedding to Carolyn Bessette nearly three years ago.

Congregation

Stephen Sackur reports: This memorial service was in a sense a national event

Dr Richard Freeman and his wife, Ann, the stepfather and mother of the Bessette sisters, were among the first mourners to arrive, about 90 minutes before the service began.

The congregation also included former heavyweight boxing champion Muhammed Ali, the actor Arnold Schwarzenegger and his wife Maria Shriver, the daughter of President John F Kennedy's sister Eunice.

The renowned economist John Kenneth Galbraith, who served as adviser to President Kennedy and was ambassador to India during his administration, was also amongst the mourners.

America's Catholics grieving for Mr Kennedy

Crowds of people lined the streets to watch the cavalcade of mourners sweep by in black limousines. Some New Yorkers had got up in the middle of the night to get the best vantage points.

The memorial service itself was closed to the media and no cameras or microphones were permitted to record the ceremony.

The private family memorial was in sharp contrast to Thursday's public service attended by more than 4,000 people at Old St Patrick's Cathedral - a Catholic church in New York's Little Italy neighbourhood.

Committed to the sea

On Thursday morning, the Kennedy family scattered the ashes of the three victims at sea, close to where they met their death.

The ceremony was conducted on the USS Briscoe off Martha's Vineyard about three miles from where the bodies were found.

Two navy chaplains and Rev O'Byrne performed a simple ceremony before the ashes and three wreaths with red, yellow and white flowers were cast into the waves.