Protesters in India's eastern state of Bihar damaged public property and ransacked offices in a railway station on Saturday to express outrage at a new military recruitment policy, demanding the government reverse course, officials said.

Thousands of young men attacked train coaches, burned tyres and clashed with officials at the station in one of India's poorest states.

At least 12 protesters were arrested and at least four policemen were injured, said Sanjay Singh, a senior police official in Bihar overseeing law and order.

“Around 2,000 to 2,500 people entered the Masaurhi railway station and attacked the forces,” Singh told Reuters.

The Agnipath or “path of fire” system aims to bring more people into the military on four-year contracts to lower the average age of India's 1.38 million-strong armed forces and cut burgeoning pension costs, the government said.

Protesters, mainly young men, say the plan will limit opportunities for permanent jobs with the defence forces, which guarantee fixed salaries, pensions and other benefits.

Some retired military officials said the government's money-saving plan risks eroding the honour of serving the nation and the safety of India.

Reports of sporadic unrest in several parts of India prompted Prime Minister Narendra Modi's government to hold meetings to review the policy of hiring soldiers for shorter tenures.

'Human resource transformation'

The scheme calls for retaining 25 per cent of the recruited soldiers after four years of service, with the rest getting priority for such jobs as with the state police.

In Uttar Pradesh, India's most populous state, police arrested at least 250 people under what are called preventative arrests. Some demonstrators accused the police of using excessive force. One person was killed in protests this week.

Defence Minister Rajnath Singh met with the chiefs of the three armed forces at his residence in New Delhi as demonstrations continued, Reuters TV partner ANI reported.

Singh has appealed to young people to apply under the new scheme.

The navy chief said on Friday the protests were unexpected and probably the result of misinformation about the new system.

“I didn't anticipate any protests like this,” Admiral R. Hari Kumar told ANI. “It is the single biggest human resource management transformation that has ever happened in the Indian military.”

Top defence officials said the plan was justified as the domain of warfare was changing and the forces need younger, more tech-savvy people.

In a bid to contain the public rage, the government said on Saturday it would reserve 10pc of the vacancies in the paramilitary forces and Assam Rifles, a unit in the Indian army for those who had passed out of the army after the four-year period mandated in the scheme.