Six people are now reported to have been killed during yesterday's rioting in the Tongan capital Nuku'alofa.
The deaths were said to have occurred when the offices of the Shoreline power company were destroyed by fire.
Police Commander Sinilau Kolokihakaufisi said six bodies had been found inside by police at the Shoreline and Tonfon offices, Radio New Zealand International reported.
The Associated Press reported Tongan Lord Chamberlain Filikepi saying the dead were believed to be looters or rioters, as staff of the power company were all accounted for after the building was torched.
Akanesi Makakaufaki of Vaiola Hospital said the remains of the six found in the Shoreline office were at the morgue.
"Five or possibly six people appear to have been killed," Australian Foreign Minister Alexander Downer told ABC radio.
Downer said the situation was serious, and Australia and New Zealand had troops and police on standby to fly to Tonga, but Tongan authorities have said they can control the situation.
An uneasy calm was holding in Nuku'alofa today after it was reported the government bowed to a wave of violent pro-democracy protests.
AP reported police and troops had taken control of central Nuku'alofa.
But New Zealand's High Commissioner to Tonga, Michael McBryde, said around lunchtime today that the atmosphere remained very tense and unpredictable.
He said the 300 to 400 New Zealanders living in Tonga are being contacted by the High Commission though many are unaffected as they are on outer islands.
Air New Zealand has cancelled today's flight to Tonga and the next scheduled service is now due at 9.30am tomorrow.
In an announcement this afternoon, the airline said: "Air New Zealand remains cautious about the safety of visitors to Tonga following discussions with the New Zealand High Commissioner in Tonga this morning."
The apparent Tongan government climb-down last night came after a day of tension in the capital, where rioting crowds overturned cars, looted and set fire to shops and offices, and stoned government buildings including the prime minister's office.
Osi Maama, editor of the Tongan Times, had told Newstalk ZB earlier this morning that the rioting was continuing and had spread outside the capital. Chinese-owned shops were being targeted and the police had been powerless to help, he said.
Radio New Zealand International correspondent Mateni Tapueluelu added: "The main shopping centre is burned out in blocks, including the prime minister's own shopping centre, they looted that, started drinking the beer and from there no one could control them."
Mr Downer earlier said Australia was considering whether to send in security forces to restore order and Foreign Minister Winston Peters said New Zealand would consider any appeals for help.
Late on Thursday evening, however, the Tonga-Now website quoted prominent pro-democracy member of parliament Akilisi Pohiva claiming victory and urging demonstrators to stop looting and go home.
The government had agreed to new elections in 2008 in which a majority of the parliament would be directly elected by popular vote, it said. Under the current system, nobles and appointed MPs outnumber the elected representatives.
Last night, Prime Minister Fred Sevele would not comment to the Herald on the group's demands. He said his cabinet would meet today.
Earlier in the day, witnesses said, police and firefighters had been powerless to control the mobs or the fires they started.
"It's scary," witness Linny Folau told the Matangi Tonga online magazine, saying rioters were jumping and dancing to loud music in a park opposite parliament.
Clouds of black smoke hung over large areas of the normally sleepy capital, including the offices of the company Shoreline, partly owned by King George Tupou V, one witness told Reuters.
Rioters had also attacked some Chinese-owned businesses, the witness said. "Police did not appear to have control, but were trying to help those trapped in offices to leave the town."
There were no reports of injuries or arrests.
The rioting began after parliament went into recess for the year without voting on proposals for sweeping democratic reforms to Tonga's semi-feudal system.
New Zealand and Australia condemned the violence and warned their nationals in Tonga to stay away from large gatherings.
"Resorting to violence and arson in the name of democratic reform cannot be tolerated," Mr Peters said in a statement. "It is straight-out criminality."
Mr Peters said New Zealand, which has long-standing links with Tonga and a large expatriate Tongan community, would help the island nation to recover from the violence and damage, but for now the issue was a domestic matter.
Mr Downer, speaking in Hanoi where he is attending an Asia-Pacific forum meeting, said he had been in touch with Tongan authorities during the day and continued to watch developments.
"I had a conversation during the afternoon with the prime minister of Tonga and he would like us to keep a close eye on the situation there, and we'll speak again tomorrow," said Downer.
"Whether we will need to provide the Tongans with any additional security in this environment we're not sure at this stage, we're just having a look at that," he added.
"We'll have a look at what the situation is like tomorrow and talk to the New Zealanders and talk to the Tongans again."
Tonga, a group of 170 coral and volcanic islands about 2,000km north of New Zealand, saw unprecedented protests in May 2005, when 10,000 people -- a tenth of the population -- took to the streets demanding democracy and public ownership of key assets. In August 2005 public servants staged a six-week strike over pay that halted services at hospitals and schools.
When he succeeded his late father in September, King Tupou V signalled some democratic changes.
The royal family said in a rare public statement in October that the Anglophile new king, educated at Oxford University and the Sandhurst military academy, believed Tonga's political system was not evolving quickly enough.
There are no universal elections in Tonga, where 10 of the 14 cabinet posts in government are appointed by the monarchy for life. Two of the remaining four posts, chosen from elected members of the Legislative Assembly, are reserved for "nobility".
- NZPA, REUTERS, NZHERALD STAFF, NEWSTALK ZB