During a political career that began more than three decades ago, Pohiva helped wrest power from the royal family and bring greater democracy to the small Pacific island nation.

He died last week in Auckland after being medically evacuated to New Zealand. He was 78.

Former lawmaker Teisina Fuko, who attended the funeral, said Pohiva was very close to the Tongan people.

"People remembered him as a spearhead for change, for creating a more democratic government," he said.

Children stood along the roads in the capital Nuku'alofa as Pohiva's family and members of the Tongan royal family followed a hearse into the Centenary Church grounds. One mourner held a sign that described Pohiva as "My Hero."

Delegations from Australia and New Zealand attended the service.

Pohiva was first elected to Tonga's parliament in 1987. He became prime minister in 2014 and won re-election three years later. His recent tenure was marked by bouts of ill health and political unrest.

Officials say he will be remembered as a champion of democracy who helped bring about democratic reforms that were incorporated into the country's constitution in 2010.

He was also known for his fight against global warming. Archipelagos like Tonga, which has 171 islands and is home to 106,000 people, are particularly vulnerable to rising seas.

In 2013, Pohiva became the first Pacific Islander to win the Defender of Democracy Award, presented by New York-based nonprofit Parliamentarians for Global Action.

Prior to being medially evacuated to New Zealand, Pohiva had been hospitalised in Tonga for two weeks suffering from pneumonia before his condition turned critical.

Lawmaker Semisi Sika has taken over as Tonga's acting prime minister.

Fuko said the political unrest will likely continue in Tonga as various factions vie for influence and power.

Australian Associated Press