Chinese authorities have arrested 13 people for Internet posts that sparked a rare protest in Beijing, highlighting tensions between officials and migrant workers, police said.

The 13 held include the boyfriend of Yuan Liya, a 22-year-old woman who fell to her death from a shopping mall, igniting the hours-long protest by hundreds of people earlier this month, Beijing police said late Tuesday.

The detentions come weeks after China's top Internet administrator announced a crackdown against "online rumours" which has seen the social media accounts of several prominent government critics closed.

The boyfriend "used the internet to spread news about the 'mysterious death'" and encouraged people to mass at the Jingwen mall, police said using a verified account on Sina Weibo, a website similar to Twitter.

Online commentators alleged that Yuan had been gang-raped and thrown from the building to her death, but police say she jumped and their initial investigations ruled out sexual assault and murder.

Images showed hundreds of police, some armed, sent to control the demonstrations, which were not violent. Most of the protesters were migrant labourers from the eastern province of Anhui, Yuan's place of birth, locals said.

Migrants have flocked to the capital for decades in search of higher incomes, but are denied the same access to health and housing services as Beijing residents and sometimes report discrimination from police.

China sees tens of thousands of small- and large-scale protests each year over a range of issues from unpaid wages to government-backed land grabs in the countryside, but major demonstrations are rare in Beijing.

Analysts say most protests are sparked by specific cases of perceived injustice. Rumours that police had beaten a migrant street vendor to death in 2011 sparked riots in the southern city of Zengcheng.