Solomon Islands Prime Minister Manasseh Sogavare sought to deflect attention from domestic issues by blaming outside interference for stirring up the protesters, with a thinly veiled reference to Taiwan and the United States.

External pressures were a "very big ... influence. I don't want to name names. We'll leave it there," Sogavare said on Friday.

Honiara's Chinatown and its downtown precinct were focuses of rioters, looters and protesters who demanded the resignation of Sogavare, who has intermittently been prime minister since 2000.

He has been widely criticised by leaders of the country's most populous island of Malaita for a 2019 decision to drop diplomatic ties with Taiwan in favour of mainland China.

His government, meanwhile, has been upset over millions of dollars in US aid promised directly to Malaita, rather than through the central government.

The Solomon Islands, with a population of about 700,000, are located about 1500 kilometres northeast of Australia. Internationally they are probably still best known for the bloody fighting that took place there during World War II between the US and Japan.

Riots and looting erupted on Wednesday out of a peaceful protest in Honiara, primarily of people from Malaita demonstrating over a number of grievances. Police fired tear gas and rubber bullets at the demonstrators, who set fire to the National Parliament, a police station and many other buildings.

Protesters defied a lockdown declared by Sogavare on Wednesday to take to the streets again on Thursday.

Critics also blamed the unrest on complaints of a lack of government services and accountability, corruption and Chinese businesses giving jobs to foreigners instead of locals.

Since the 2019 shift in allegiance from Taiwan to China there has been an expectation of massive infrastructure investment from Beijing - locally rumoured to be in the range of $500 million - but with the outbreak of the COVID-19 pandemic shortly after the shift, none of that has yet materialised.

Malaita threatened to hold a referendum on independence over the issue, but that was quashed by Sogavare's government.

Sogavare on Friday said he stood by his government's decision to embrace Beijing, which he described as the "only issue" in the violence, which was "unfortunately influenced and encouraged by other powers."

"I'm not going to bow down to anyone. We are intact, the government's intact and we're going to defend democracy," he said.

A plane carrying Australian police and diplomats arrived late on Thursday in Honiara to help local police restore order.

Up to 50 more Australian police as well 43 defence force personnel with a navy patrol boat were scheduled to arrive on Friday.

They were requested by Sogavare under a bilateral treaty with Australia, and the presence of an independent force, though small, seemed to help quell some of the violence.

Australia has a history of assisting the Solomon Islands, stepping in after years of bloody ethnic violence known as "the tensions" in 2003. The Australian-led international police and military force called the Regional Assistance Mission to Solomon Islands helped restore the peace and left in 2017.

The Australian personnel are expected to be on hand for "a matter of weeks," according Australian Foreign Minister Marise Payne.

Payne told reporters on Friday that she had no indication that other countries had stirred up the unrest.

"We have not indicated that at all," Payne said.

Australia is not assisting in the protection of the National Parliament and the executive buildings, in a sign that it was not taking political sides.

"We've been very clear. Our view is we don't want to see violence," Payne said. "We would very much hope for a return to stability."

Australian Prime Minister Scott Morrison questioned whether Chinese citizens and businesses were being targeted. He described the unrest as "a bit of a mixed story" and noted Chinatown was the scene of rioting before Australia's 2003 intervention.

Chinese Foreign Ministry spokesperson Zhao Lijian on Friday condemned the violence and stressed Beijing's support for the Solomon Islands government. He said China was taking measures to safeguard the safety and rights of Chinese people and institutions in the country.

"We believe that under the leadership of Prime Minister Sogavare, the Solomon government can restore order and stabilise the internal situation as soon as possible," he said.

The establishment of diplomatic ties with Beijing "has won sincere support of the people," and "any attempts to undermine the normal development of China-Solomon relations are futile," Zhao said.

Australian Associated Press