Indian police have arrested more than 500 people ahead of a Supreme Court ruling on a religious site in Ayodhya, media reports said, with authorities fearing the verdict could trigger unrest.

The decision on the future of the site is due by November 17 and thousands of paramilitaries have already been sent to the northern city.

Hindu hardliners want a temple built on the site, currently barricaded off decades after a 16th-century Babri Mosque there was demolished by the Hindu zealots during 1992 riots that left 2,000 people dead.

Security is being tightened across India in the run-up to the ruling and Uttar Pradesh state police chief O.P. Singh told the Economic Times that more than 500 arrests had been made.

"The main message to the police force is to maintain peace at any cost," the newspaper quoted him as saying.

Most of the suspects were taken into custody while a further 70 people were detained over their social media posts, he said - warning the internet could be blocked in the region if required.

Singh added that police had also identified more than 10,000 people he described as "anti-social".

A police spokesman declined to comment to AFP.

In recent years Ayodhya has become a rallying point for Prime Minister Narendra Modi's ruling Hindu-nationalist Bharatiya Janata Party (BJP).

Some senior BJP members are being tried separately over their role in the mosque's 1992 destruction.

In 2010, a High Court divided the disputed land between Hindu and Muslim groups but both parties appealed to the Supreme Court which has since repeatedly put off a verdict.

For minority Muslims, the dispute and a recent clampdown in Muslim-majority Kashmir have become symbols of the hostility that they say they face from the government. Hindus make up about 80 percent of India's 1.3 billion population while there are about 200 million Muslims.

Copyright Agence France-Presse, 2019