Tens of thousands of police were deployed across India on Saturday in a bid to smother new protests by farmers fighting government agriculture reforms.

Ten metro stations were closed in central New Delhi -- where a tractor rally last month turned into a violent rampage -- and thousands of police manned barricades and roadblocks at key intersections.

Farmers unions called for protest roadblocks across the country in the latest day of action.

They and their supporters occupied dozens of roads and toll booths for three hours in several states but no trouble was reported.

A major police deployment was ordered in the key farm state of Uttar Pradesh, which is a traditional pro-government bastion. Farmers groups suspended their action in the state to avoid a confrontation. 

Tens of thousands of farmers have been camping on the outskirts of Delhi since November calling for a repeal of the reforms that free up farm produce markets.

The farmers say the changes mean the crucial agriculture industry will be taken over by major conglomerates.

While the authorities have increased pressure on the Delhi protest camps -- cutting internet and water supplies -- the farmers have vowed to keep their campaign going for months more.

Rakesh Tikait, one of the senior farmers' leaders, said Saturday that the protests would go on until the October 2 one-year anniversary of the launch of their campaign unless the government repealed the new laws.

He told the Indian Express newspaper that thousands more farmers wanted to come to Delhi to join the protests and would not be deterred by barbed wire fences put around the camps.

"They can put nails on the ground; we will put soil over it and grow flowers. We aren't scared of the barricading or high security.

"We don't think police will seal the area. If they do, there are protesters here who can break through all the barricades," he said.