International troops secured the airport in Tonga's riot-scarred capital, but commercial flights out for frightened foreigners were not expected to resume for a day due to church services in the heavily Christian country, commanders said Sunday.

About 150 police and soldiers from Australia and New Zealand arrived Saturday in the impoverished South Pacific country, after a mob rampage on Thursday killed at least eight people and left most of the capital's business district a burned-out wreck.

Tongan Prime Minister Fred Sevele on Sunday rejected calls for his resignation in the wake of the destruction.

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Pro-democracy leaders claim Sevele and his government were responsible for delays in implementing political change that helped foment the violence.

"Government is not to be blamed for what happened on Thursday," Sevele told New Zealand's TV3 News.

"I don't think anyone ever thought ... things would get out of hand," he said. "It's a day of shame for us Tongans."

The violence was triggered by anger that Parliament might finish this year's session on Thursday without settling plans to introduce reforms that would give democratically elected lawmakers a parliamentary majority over royally appointed legislators.

After the riots started, the government on Thursday rapidly agreed to a plan ensuring that 21 lawmakers in the 30-seat Parliament will be elected starting in 2008 -- for the first time giving elected members a majority over those appointed by the king.

New Zealand Prime Minister Helen Clark said deploying foreign forces was about maintaining peace, not propping up Tonga's feudal political system.

"I should stress this is not about supporting any one side or another in Tonga," Clark told reporters on the sidelines of a Pacific Rim summit in Vietnam. "This is about supporting a proper process of constitutional reform.

"Tonga has been a feudal monarchy and there's no place for that in the 21st century," she said.

Leading pro-democracy lawmaker 'Akilisi Pohiva said frustration at the slow rate of change sparked the outburst of rage.

"I think it had come to a point where people became very, very angry, very upset -- and they could no longer control themselves," he told TV3 on Sunday.

Rear Adm. Jack Steer, commander of New Zealand's defense forces, which are leading the international contingent, said the airport was able to operate.

"However, the Tongan government has, as per their normal routine, closed the airport while airport staff observed Sunday religious activities along with the rest of the Tongan community," Steer said.

Air New Zealand announced it would fly to Tonga on Monday, and other carriers were expected to resume services. International airlines canceled scheduled flights to Tonga last week due to the security risk.

Lt. Col. Darren Beck, the New Zealand commander in Tonga, described the situation as "calm."

Australian Foreign Minister Alexander Downer said he hoped the mission would be short.

"Hopefully, there won't be any more problems and we'll be able to withdraw fairly soon," he told Australian Broadcasting Corp. television.

Downer said any of the 300 Australians in Tonga can be evacuated if they wish.

"That's up to them. Some of them feel a bit nervous depending on who they work for ... and others feel perfectly safe," he said.

Tonga, halfway between Australia and Tahiti, has about 108,000 people. Its economy depends on pumpkin and vanilla exports, fishing, foreign aid and remittances from Tongans abroad.