Australian troops are arriving in the Solomon Islands to help restore peace after rioting and looting in the capital, Honiara.
Hundreds of demonstrators marched on the government building on Wednesday, demanding the Prime Minister-elect, Snyder Rini, stand down.
Parts of Honiara are in ruins following rioting on Tuesday, and demonstrators have threatened more destruction.
Mr Rini denies claims he is corrupt and favours Chinese businessmen.
Much of Honiara's Chinatown area was razed overnight and some families were forced to jump from burning buildings. Police have imposed a dusk-to-dawn curfew on the city.
Mr Rini emerged from a meeting with advisers on Wednesday to appeal to Honiara residents to "remain calm", reported AFP news agency.
In an earlier statement he invited protesters to engage in dialogue with him, but did not respond to the demands that he should resign, said the agency. His swearing-in, originally set for Wednesday, has been postponed.
Some 180 Australian soldiers and police have begun arriving in the country to try to impose order after a written request from the Solomons government. A smaller contingent of additional New Zealand peacekeepers are set to arrive on Thursday.
But the BBC's Phil Mercer says there are concerns that the presence of more foreign troops could inflame the situation in the troubled city.
About 280 Australian police were already in the country as part of a regional force sent to restore peace in 2003, after violence stirred up by local warlords left hundreds dead and 20,000 displaced.
Wednesday's rioting came after newly-elected MPs met in secret to elect a new prime minister.
Mr Rini, 56, beat off two main rivals in Tuesday's secret ballot for the leadership - former Prime Minister Manasseh Sogavare and Job Dudley Tausinga, leader of the new Rural Advancement Party.
He is accused of being too closely linked to former Prime Minister Allan Kemakeza's administration, which was tainted by corruption allegations.
Mr Rini did not refer to demands that he stand down
Demonstrators also claim that the new government is heavily influenced by the Taiwan government and local Chinese businessmen.
On Wednesday a political opponent of Mr Rini alleged MPs had been paid to vote for him, the Solomon Star newspaper reported.
"Some of this rioting was sparked by allegations made by Snyder Rini's political opponents that he was in receipt of Chinese, meaning I think largely Taiwanese, money," Australian Foreign Minister Alexander Downer reportedly told Australian television.
But Mr Rini denied there had been any "influence by outsiders", in a report on the Solomon Star website.
"Some Solomon Islanders have been resentful of the Chinese," said government spokesman Johnson Honimae.
"[The Chinese] were taking up all the businesses in town and all the staff and prices were increasing unreasonably. It's something that people have been holding within them," he said.
But Solomons police chief Shane Castles said protesters' complaints about the election had quickly descended into "opportunistic robbery and looting", according to AP news agency.
AP reported a government official as saying Mr Rini was being held in a secret location.
The BBC's Phil Mercer says the lawlessness in Honiara has taken the authorities by surprise.
The security situation across the Solomons archipelago had improved since the Australian-led mission arrived in 2003, after years of tribal violence had resulted in the breakdown of law and order.
The conflict - between indigenous residents of the main island of Guadalcanal and settlers from the island of Malaita - was fought over land rights and jobs.
But what the foreign forces have been unable to soothe are the political tensions that have for many years divided this troubled South Pacific nation, our correspondent says.