Tongan authorities accused of human rights violations. 13/12/2006. ABC News Online

There are calls for the international community to investigate allegations of torture and abuse of prisoners after last month's riots in Tonga that claimed six lives.

Authorities have detained about 600 people, including children, while the state of emergency in Nuku'alofa has been extended until the middle of next month.

Tonga's military and police have been granted an extension of emergency powers in the interests of public order and safety in the Kingdom.

However a report by Tonga's National Centre for Women and Children accuses the same authorities of a systematic campaign of human rights violations.

The author of the report is Australian Gus McLean.

"People being arrested and having unreasonable force being used against them during their arrest, people are being held in detention incommunicado," he said.

"They are not being allowed to contact their lawyers, children detained have not been allowed to contact their parents."

A UN investigator is due in Tonga next week to investigate the allegations of abuse and the progress of the criminal investigations.