WASHINGTON (REUTERS) - United States President Joe Biden has nominated Ms Caroline Kennedy to be US ambassador to Australia, and Olympic figure skater Michelle Kwan as ambassador to Belize, the White House said.

Ms Kennedy, 64, is the daughter of the country's 35th president, John F. Kennedy, who was assassinated in 1963.

She previously served as US ambassador to Japan from 2013 to 2017 under former president Barack Obama.

Ms Kwan is the winner of two silver Olympic medals in figure skating. She has served as an adviser to the US Department of State on women's issues.

Australia is a key ally of the US and that relationship has strengthened in response to China's growing power and increasingly assertive behaviour in Asia and beyond.

Ms Kennedy's experience in Japan should be helpful in Canberra given that Australia and Japan are both members of the Quad grouping, which includes the US and India, that has been expanding cooperation in the face of China's rise.

In September, the US, Britain and Australia announced a security pact dubbed Aukus that will help Australia acquire US nuclear-powered submarines and expand its security reach in the Indo-Pacific region.

Ms Kennedy was the first female US ambassador to Japan. She trained as an attorney and has co-authored books on civil liberties and edited anthologies of poetry.

It was unclear when Ms Kennedy might be confirmed in her post, which requires Senate approval. Senate Republicans have been blocking dozens of Mr Biden's nominees for diplomatic posts.