NUKU'ALOFA, Tonga, Dec 9, 2024 (BSS/AFP) - Tonga's Prime Minister Siaosi Sovaleni abruptly resigned on Monday, his office and parliament officials said, stepping down in the wake of a power struggle with the Pacific nation's royal family.

"Yes, the prime minister has resigned but we're not sure what happens next," parliament official Rhonda Hufanga told AFP.

Sovaleni told parliament he would quit just moments before lawmakers decided his future in a vote of no confidence.

It was not immediately clear who would replace Sovaleni, who has occupied the top job since 2021, although the no-confidence vote was led by rival and veteran politician 'Aisake Eke.

Asked to confirm Sovaleni's resignation, a spokeswoman from the prime minister's office told AFP: "It's true."

Tonga has been a constitutional monarchy since the late 19th century.

Although the royals have slowly relinquished some of their powers, the Tongan king and his fellow nobles remain figures of considerable influence.

Sovaleni gave up the armed forces portfolio earlier this year after running afoul of King Tupou VI, who said the prime minister no longer enjoyed his "confidence and consent" in the role.

Initially, the prime minister refused to heed the king's request, citing legal advice that any move to strip him would be unconstitutional.

But Sovaleni eventually backed down in April after he was forced to deny allegations of insulting the king.

Since then speculation has been rife about a growing rift between the royals and Sovaleni's government.

- Noble power -

Tonga overhauled its constitution after pro-democracy protests in 2006, which spiralled into angry riots that razed swathes of the capital Nuku'alofa.

At the time, the Tongan king held immense sway as the country's head of state, head of government, and military commander-in-chief.

Although the monarchy eventually agreed to devolve much of its responsibility to a cabinet of elected lawmakers, its power has not been totally diluted.

Tonga's hereditary nobles still elect nine members in the country's 26-seat legislative assembly.

A developing country of some 106,000 people spread across dozens of islands, Tonga's debt-laden government is seen as particularly vulnerable to economic pressure from China.

The island kingdom owes China's export bank around $130 million -- almost a third of its GDP -- which was loaned to help rebuild after the 2006 riots left Nuku'alofa in ruins.

Repayments on that loan were scheduled to start spiking this year.

Sovaleni studied computing at Oxford and has a master's in business administration from the University of the South Pacific.

He was first elected to parliament in 2014 and served as deputy prime minister from 2014-17, then became education minister in 2019.