Police helped people flee the violence and tried to protect property but made no effort to arrest rioters, said Mary Fonua of the Matangi Tonga news Web site.

As night fell, some semblance of order began returning to the city center. But looters continued carrying goods from wrecked stores. Fires burned unchecked in buildings in several parts of the city and torched cars lay wrecked and smoldering on the streets

The rioting began after thousands of people met in Nuku'alofa, capital of the island nation halfway between Australia and Tahiti, and demanded that parliament pass democratic reforms before it ends its annual session today. The meeting in the capital was addressed by pro-democracy lawmakers pressing for democratic change.

The rioters smashed windows in Prime Minister Fred Sevele's offices and other government buildings, including Parliament House, the Magistrates' Court, the Public Service Commission Office and the Finance Ministry. It was not known if the prime minister was in the office at the time.

Rioters also overturned shelves and stripped stock from a mid-city supermarket owned by Sevele.

New Zealand Foreign Minister Winston Peters branded the rioting and arson "a disaster for Tonga ... and a severe setback at a time when political reform is happening in Tonga."

"There is no way anybody interested in political reforms will advance their cause by criminal actions," he told National Radio from the Vietnamese capital, Hanoi, where he's attending the Asia Pacific Economic Cooperation foreign ministers' meeting.

New Zealand would offer assistance, he said, adding that he hoped those responsible would be punished.

Fonua said the office of the Shoreline power company had burned to the ground, and that the Pacific Royale Hotel had been "trashed" by hundreds of rampaging youths.

The government did not comment on the rioting.

Tonga's King Siaosi Tupou V was believed to be at a royal villa outside the capital today.

Last month, a government committee recommended that all lawmakers in Tonga be elected. Only nine lawmakers in the 32-seat parliament are now elected by popular vote — with the rest appointed by the king and noble families.

The recommendation was a significant step in the accelerating efforts to reform the kingdom's political system since the September death of King Taufa'ahau Tupou IV, who was in power for more than 40 years.

Sevele, who is appointed by Tonga's king, is seen as complicit in delay of the reforms, along with most of the island nation's political establishment.