The protests come at a crucial time for India, where national elections are due in the coming months and Prime Minister Narendra Modi’s party is widely expected to secure a third successive term in office.

The farmers began their protest last week but were stopped some 200km (125 miles) from the capital. The authorities are determined to contain the protests, which have renewed the movement from more than two years ago when tens of thousands of farmers had camped out on the outskirts of the city for more than a year.

At the time, the farmers pitched tents, bought food supplies and held out in the sit-in until they forced Modi to repeal new agriculture laws in a major reversal for his government.

This time around, the authorities have barricaded the highways into New Delhi with cement blocks, metal containers, barbed wire and iron spikes to prevent the farmers from entering.

On Wednesday, the farmers arrived at the barricades with bulldozers and excavators to try and push through.

Last week, the farmers had paused their protest and hunkered down near the town of Shambhu, close to the border between the northern states of Punjab and Haryana, as unions engaged in discussions with government officials.

They rejected a proposal from the government that offered them five-year contracts of guaranteed prices on a set of certain crops, including maize, grain, legumes and cotton, and the farmers resumed their march on Wednesday.