Indian authorities have suspended internet services and barred political leaders from entering a northern town to calm tensions after eight people were killed in a deadly escalation of a year-long demonstration against agriculture laws.

Four farmers died on Sunday when a car owned by junior home minister Ajay Mishra ran over protesters in the Uttar Pradesh town of Lakhimpur Kheri, officials and farm leaders said.

Mr Mishra said his driver and three members of the ruling Bharatiya Janata Party who were in the car were killed by protesters in the violence that broke out after the incident.

"They were beaten to death by the farmers," he said in a statement.

Farm leaders alleged that Mr Mishra's son was in the car when it ran over the protesters, but he denied it.

Police on Monday said they had arrested six people and filed a criminal complaint against 14 more, including the minister's son, in connection with the death of the four farmers.

The BJP also lodged a criminal complaint against the farmers over the death of its members and the driver, said Arvind Chaurasia, a senior official in charge of the district.

Police also said they had recovered the body of a local journalist from the spot where the violence broke out but did not provide further details.

Farm leaders are demanding a judicial investigation and compensation for the families of the dead farmers. They also want action against the minister and his son, saying Mr Mishra should be removed from office.

The violence marked an escalation in protests against agriculture laws that farmers say will shatter their livelihoods. The protests have lasted since the government passed the laws last September and have been one of the biggest challenges to Prime Minister Narendra Modi.

Last week, thousands of farmers gathered at the edges of the capital New Delhi to mark one year of demonstrations.

The government says the changes in the laws were needed to modernise agriculture and boost production through private investment, but the farmers say the laws will devastate their earnings by ending guaranteed pricing and will force them to sell their crops to corporations at cheaper prices.

Police officer Arun Kumar Singh told the Associated Press that all schools have been shut in the district and people have been advised to stay indoors following the violence in Lakhimpur Kheri, 120 miles south east of Uttar Pradesh's capital, Lucknow.

Authorities also barred leaders from various opposition parties from entering the district to meet the farmers amid concerns it could cause further disorder.

Rakesh Tikait, a senior farming leader, said the bodies will not be cremated until the government accepts their demands.

The protests have been largely peaceful, though clashes in January left one protester dead and hundreds injured after demonstrators broke through police barricades to storm a historic fort in Delhi.

Thousands of farmers have camped for nearly a year on the outskirts of New Delhi, and more than a dozen rounds of talks between the government and the farmers have failed to resolve the issues.