Hardik Patel, who led recent protests in Gujarat from the Patidar caste demanding preferential treatment over jobs and university places, attends a press conference in New Delhi on Sunday.

AFP/New Delhi

A firebrand protest leader vowed on Sunday to spread agitation over caste preferences nationwide, just days after the worst violence in more than a decade in western India left nine people dead.

Hardik Patel said he was gathering support to hold protests in New Delhi and the northern city of Lucknow, after arriving in the national capital to meet leaders of various castes in India's rigid social hierarchy.

"We will take the movement all over the nation and turn it into a country-wide movement," the 22-year-old self-styled leader told reporters after landing from the western state of Gujarat.

"This is going to be a long fight."

India was forced to call in the army on Wednesday following riots and arson across Gujarat after a mass rally in the state's main city of Ahmedabad turned violent.

Patel, who was briefly arrested, led the rally of an estimated half a million people demanding special treatment for the Patidar or Patel caste.

The Patidars are one of the state's most affluent communities, but they say they are struggling to compete with less privileged castes for government jobs and university places.

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

But the policy of "reservation" causes resentment among other communities who say it freezes them out.

"Due to reservations, the country is 60 years behind. The government needs to give reservations to all the needy communities," Patel said on Sunday.

Local media said it was the first time the army had been deployed in Prime Minister Narendra Modi's home state of Gujarat since communal riots in 2002 left at least 1,000 people dead.

Modi appealed for calm immediately after last week's violence. The scale of the protest movement appears to have taken political leaders by surprise, after beginning earlier this year and rapidly gathering pace in recent weeks.