Indonesia has sent hundreds of riot police to a tiny island, an official said Friday, after protests broke out against a China-backed project that would displace thousands of residents.

Around 1,000 people protested in Batam City on Monday over a plan to develop Rempang island into a Chinese-funded economic zone, including the construction of a multibillion-dollar glass factory, that would displace around 7,500 people.

Some protesters clashed with security forces outside a government agency, wielding machetes, Molotov cocktails and stones, police said, adding that dozens were arrested.

Beijing has poured money into infrastructure and resource projects in Southeast Asia's biggest economy and its investments have previously caused social unrest, including a deadly January riot at a nickel smelting facility on Sulawesi island.

Police in Riau Islands province, near Singapore, said that 200 officers from the mobile brigade riot police unit known as Brimob, notorious for its heavy-handed tactics, were dispatched to the scene on Thursday.

"They are from Riau province's mobile brigade (unit). The deployment is… to create security," spokesman Zahwani Pandra Arsyad told AFP.

"This is a precautionary step to… maintain security as Batam, Riau Islands is strategic (for) people to do business and invest."

Arsyad said the length of deployment "depends on the situation".

Monday's unrest took place outside BP Batam's building, the agency that oversees the region's development.

Jakarta secured a reported $11.5 billion investment pledge from Xinyi Glass Holdings, the world's biggest glass producer, to build the factory during a visit by President Joko Widodo to the Chinese city of Chengdu in July.

Widodo responded to the unrest on Thursday, saying anger against the project was caused by miscommunication that could have been prevented if relocation package details were properly explained.

BP Batam has said the packages will include rent and meal compensation.

The government says the development will create tens of thousands of jobs for Indonesians.

It aims to attract more than 300,000 jobs by 2080, according to officials, who have not said when the project is expected to be finished.