Washington (AFP) - Former US president George W. Bush shared a light moment with former First Lady Michelle Obama at the funeral for his father George H.W. Bush on Wednesday, appearing to slip her a piece of candy before the service began.

The 43rd US president had also given Michelle Obama a mint during the memorial service in September for Arizona Senator John McCain.

As the 72-year-old Bush arrived at the National Cathedral for the state funeral for his father -- the 41st US president -- he shook hands with President Donald Trump and his wife, Melania.

Bush then shook hands with former President Barack Obama and Michelle Obama, causing her to smile when he passed her what appeared to be a piece of candy.

Bush then continued down the row, shaking hands with former president Bill Clinton, former First Lady Hillary Clinton, former president Jimmy Carter and his wife, Rosalynn.

Michelle Obama later explained the exchange at the McCain memorial during an interview on NBC's Today show.

"We are forever seat mates because of protocol," she said of Bush. "That's how we sit at all the official functions so he is my partner in crime at every major thing where all the formers gather.

"So we're together all the time, and I love him to death. He's a wonderful man. He's a funny man," she said.

George H.W. Bush died on Friday at the age of 94.