Authorities in China's Guangdong province have ordered police to arrest anyone suspected of fomenting unrest after clashes between migrant workers and locals resulted in two nights of rioting.

Riots and clashes with police exploded in Zhongshan city on Monday and Tuesday nights prompting authorities to crack down on unrest and prevent the situation from escalating, the government said in a statement Thursday.

Guangdong, located next to Hong Kong and known as the "world's factory floor", has employed tens of millions of migrant workers from other provinces in recent decades, a pool of cheap labour that has driven China's export-oriented economy.

"Zhongshan city has deployed police forces to key areas in the city to enforce strict control measures against criminal suspects who provoke, strike or inflict harm," the city government said in a statement.

"Police organs must crackdown in a resolute and strict fashion at the small numbers of criminal elements that aim to provoke or make trouble.

"We must crackdown on their brazen arrogance with all of our might and prevent the situation from escalating."

The statement said no one had been "killed or seriously injured" in the two nights of rioting, but it refrained from revealing how many people had been injured or arrested.

Hong Kong and overseas Chinese news reports said hundreds had been injured and between 10 and 30 people killed in the unrest, while up to 300 people have been arrested so far.

Rioting began Monday night after police stepped in to break up fighting between migrant workers largely from Sichuan province in the nation's southwest and the locals in Shaxi township in Zhongshan.

Migrants in Guangdong have long complained of shrinking wages, discrimination and unfair social benefits meted out by local governments.

Unrest among migrant workers in Guangdong has increased in recent years.

In November last year, more than 7,000 workers went on strike at a Guangdong factory making New Balance, Adidas and Nike shoes, clashing with police in a protest over layoffs and wage cuts, a rights group said.

In June 2011, riots also erupted in the suburbs of Guangzhou, the provincial capital, after rumours spread that police had beaten a street hawker to death and manhandled his pregnant wife, both of whom were from Sichuan.