Barack Obama has joined a crowd of well-known political figures to pay his respects to Beau Biden, the eldest son of US Vice President Joe Biden.

The 46-year-old, who was married with two children, died on May 30 from brain cancer.

"Beau Biden was an original. He was a good man. A man of character. A man who loved deeply and was loved in return," Obama said.

"To know Joe and the rest of the Biden family is to understand why Beau lived the life he did."

More than a thousand people attended the service at St. Anthony of Padua Roman Catholic Church, including Bill and Hillary Clinton and first lady Michelle Obama.

Beau Biden served as Delaware attorney general and spent a year in Iraq as part of the Delaware Army National Guard. His career had been expected to follow a similar path to that of his father, until he suffered a stroke in 2010.

Three years later he was diagnosed with brain cancer and underwent chemotherapy and surgery. Earlier this year Biden was told the cancer had recurred. He died in hospital less than two weeks after being admitted.

His death is another tragedy for the vice president, who lost his wife and infant daughter in a car accident more than four decades ago. Beau survived, along with his younger brother Hunter. It's an incident that has shaped the career of Joe Biden, and helped earn him a reputation for being able to comfort others who are grieving.

Biden senior did not speak at the funeral, after entering the church with his family at the start of the service.

Obama described Beau Biden as determined to "live a life of meaning," and as belonging to a family "who brushed away the possibility of privilege for the harder, better reward of earning his own way."

The president said that following news of Biden's death, condolence letters had flooded the White House.

Chief of staff of the US Army, General Ray Odierno, said Biden lived "a life that had incredible meaning and a life that left an indelible mark on all of us."

He hailed Biden as "a father, a husband, a son, a friend, a leader, a soldier, and a patriot," posthumously awarding him the Legion of Merit for his military service.

The service ended with Coldplay lead singer Chris Martin singing one of Biden's favorite songs, "Til Kingdom Come."

Beau Biden had planned to run for governor of Delaware next year.

an/ (AP, AFP, Reuters)