Australia and New Zealand have sent troops and police officers to yet another troubled South Pacific country to help restore calm. The two countries have now deployed forces to Tonga at the request of the embattled government following riots that left at least eight people dead. 

Tonga's international airport reopened Monday thanks to the presence of 150 New Zealand and Australian troops, deployed to secure key infrastructure following violent protests.

The Tonga government is also discussing with Australia and New Zealand additional military support after last week's riots in the capital, Nuku'alofa, which ended in the looting and burning of the main business district.

Social and political problems across the South Pacific have become permanent headaches for New Zealand and Australia, the region's two most powerful countries.

Along with the violence in Tonga, there have been threats of a military coup in Fiji and continued unrest in the Solomon Islands, parts of Papua New Guinea and East Timor.

New Zealand Prime Minister Helen Clark is worried that unstable Pacific countries could be exploited by criminals and extremists.

"Everyone is aware of what 'fragile and failed states' mean in today's world. It can mean penetration of financial systems, lax borders, drug trade, financing terrorism or other activities," she said.

International criminal gangs are reported to have laundered billions of dollars on the tiny island state of Nauru in the past decade and the United States has accused the island state of selling large numbers of fake passports.

Analysts blame the instability on poverty and corruption. Lack of natural resources and the failure by government to improve social conditions fuel violence.

The Tonga riots erupted after pro-democracy groups accused the legislature of failing to move on expanding democracy in the kingdom.

The relative prosperity of some immigrants in impoverished South Pacific nations has also stirred resentment.

Police in Tonga believe there was a strong anti-Chinese dimension to Thursday's disturbances.

There were similar problems for the Chinese community in the Solomon Islands when trouble flared there earlier this year. Many Chinese shops were destroyed by rioters in the capital Honiara.

The Chinese government was planning Monday to airlift dozens of its citizens out of Tonga after looters and arsonists targeted their shops and businesses.