SYDNEY—Australia said it would send a peacekeeping force of more than 100 federal police and defense personnel to the Solomon Islands after a second day of violence in the Pacific Island nation.

Protesters have burned buildings including a police station and breached the national parliament in what Solomon Islands Prime Minister Manasseh Sogavare said was an attempt to bring his government down. Mr. Sogavare on Wednesday declared a 36-hour lockdown of the national capital, Honiara, but this failed to halt the violence and...

SYDNEY—Australia said it would send a peacekeeping force of more than 100 federal police and defense personnel to the Solomon Islands after a second day of violence in the Pacific Island nation.

Protesters have burned buildings including a police station and breached the national parliament in what Solomon Islands Prime Minister Manasseh Sogavare said was an attempt to bring his government down. Mr. Sogavare on Wednesday declared a 36-hour lockdown of the national capital, Honiara, but this failed to halt the violence and looting.

Australian Prime Minister Scott Morrison said 23 Australian federal police officers would be immediately deployed to prevent riots, with 50 more officers helping to secure key infrastructure. An additional 43 members of Australia’s defense force would arrive on Friday. He said the deployment was in response to a request for help from Mr. Sogavare.

“Our purpose here is to provide stability and security to enable the normal constitutional processes in the Solomon Islands to be able to deal with the various issues that have arisen,” Mr. Morrison told reporters late Thursday.

Around 690,000 people live on the Solomon Islands—Australia’s neighbor just across the Coral Sea. The mineral-rich Solomon Islands, which has a land area slightly smaller than the state of Maryland, has a history of ethnic tensions. Two years ago, the country switched its diplomatic allegiance to China, from Taiwan.

The Solomon Islands government’s request for help came under a bilateral security treaty signed with Australia in 2017, and Mr. Morrison said the deployment was likely to last several weeks.

“It is not the Australian government’s intention in any way to intervene in the internal affairs of the Solomon Islands; that is for them to resolve,” said Mr. Morrison.

On Wednesday, Mr. Sogavare said hundreds of people were involved in the protests, which had caused damage to buildings in the China Town and Kukum commercial areas.

Mr. Morrison said the Australian government had on Thursday afternoon received new reports of buildings burning on the main road in the center of Honiara, including a large commercial building and a bank branch, with an increasing number of people on the streets.

Write to Alice Uribe at alice.uribe@wsj.com