Indian Prime Minister Narendra Modi appealed for peace on Wednesday after a mass rally in his home state turned violent, with overnight rioting and arson.

Thousands of paramilitary troops have been sent to the western state of Gujarat to contain the violence, which broke out after an estimated half a million people rallied to demand favourable treatment for their caste.

One police officer who asked not to be named said two protesters had died in police firing on Tuesday, although this could not immediately be confirmed.

Authorities have imposed a curfew in parts of Ahmedabad and five other cities and towns after stone-throwing members of the Patidar or Patel caste torched cars, buses and police stations.

"I appeal to all brothers and sisters of Gujarat that they should not resort to violence," Modi said in a statement.

"Violence has never done good for anyone. All issues can be resolved peacefully through talks," said Modi, who served as the state's chief minister for more than a decade, in a television address delivered in his native Gujarati.

The streets of Ahmedabad were deserted on Wednesday with schools, shops and businesses closed.

But some protests continued in Surat, the centre of India's lucrative diamond trade, where local media said police used tear gas to disperse demonstrators.

The riots were triggered by the detention late Tuesday of the Patidars' self-styled firebrand leader Hardik Patel, 22, who has since been released.

At least a dozen officers were injured in the violence, prompting the first curfew in the state since 2002 when communal riots left at least 1,000 people dead, said Gujarat Director General of Police P.C Thakur.

"There was heavy stone pelting of police vehicles and torching of police stations in Unjha and Kalol towns," he said.

As many as 100 buses were torched and property damaged in the violence in the cities of Ahmedabad, Surat and Mehsana and the towns of Unjha and Visnagar, senior local officers said.

About half a million Patidars rallied in Ahmedabad on Tuesday, paralysing the city, to demand preferential treatment.

The Patidars, one of the state's most affluent castes, who make up around 12 percent of its population, say they are struggling to compete with less privileged castes for jobs.

India sets aside a proportion of government jobs and university places for Dalits, known as "untouchables", and for so-called "other backward castes" under measures intended to bring victims of the worst discrimination into the mainstream.

State authorities have already ruled out granting the Patidars' request, but their campaign has gathered pace in recent weeks.

Hardik Patel called on the police and authorities to "maintain peace" on Wednesday as he vowed to keep up the pressure.

"This is a fight for our rights... we will continue with our campaign on the roads and the streets," he said in a television interview.

Source: AFP