Barbados has officially removed Queen Elizabeth II as its head of state and became a republic in an overnight ceremony in the capital of Bridgetown.

Dame Sandra Mason was sworn in as president during a midnight event coinciding with the country's 55th anniversary of independence.

The Prince of Wales and Barbadian singer Rihanna attended the event.

In a speech, Prince Charles acknowledged the "appalling atrocity of slavery" the Caribbean island suffered.

To signify the official change of power, a final salute was made to the British monarchy and the Royal Standard flag was lowered and replaced.

Speaking as the guest of honour at the event, Prince Charles reiterated the continuing ties between the two nations despite the constitutional status change.

He described the moment as a new beginning and said he would always consider himself "a friend to Barbados" before being awarded the prestigious Order of Freedom Independence award by the new president.

Barbados announced is plan to become a republic last year, but it will remain within the Commonwealth.

Dame Sandra Mason, 72, the island's governor-general since 2018, was named as president-elect of the nation following a vote in parliament last month. She now replaces the Queen as the head of state.

"Vessel Republic Barbados has set sail on her maiden voyage. May she weather all storms and land our country and citizens safely on the horizons and shores which are ahead of us," she said after being sworn in.

Leading national figures, including Prime Minister Mia Mottley, swore allegiance to Barbados in front of the new president at the ceremony, which lasted for several hours.

She later announced that pop star Rihanna would be named a national hero by President Mason. The artist and businesswoman, whose full name is Robyn Rihanna Fenty, was previously named an ambassador by her home country in 2018.

"May you continue to shine like a diamond and bring honour to your nation," Ms Mottley said, in reference to one of Rihanna's songs.