Suspected Hindu radicals on Saturday attacked a spiritual retreat founded by a preacher who backed letting women enter a renowned Indian temple, police said.

The incident heightened tensions in southern India where police have rounded up more than 2,000 people suspected of taking part in protests to stop women from worshipping at the Sabrimala shrine.

The attackers set ablaze two cars and a scooter outside the ashram in the early morning attack in the southern city of Thiruvananthapuram, police said.

They also placed a wreath outside the retreat condemning Swami Sandeepananda Giri, its founder.

The swami had backed a Supreme Court order which ended a longstanding ban on women of child bearing age entering the temple complex.

"We are investigating the matter. No arrests have been made so far," a Thiruvananthapuram police spokesman said.

Kerala state Chief Minister Pinarayi Vijayan condemned the attack on the ashram.

In social media posts he said that such disputes had to be "dealt with at an ideological level".

"We will not let anyone take law and order into their hands," Vijayan added.

Police have launched a major search operation across Kerala state this week and said more arrests are likely as they sift through video footage of the attacks on women devotees and police near the temple.

The protests erupted as the temple opened for the first time since the Supreme Court ruled last month that women of menstruating age should be allowed to worship at Sabrimala.

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The court is to hear new petitions challenging its ruling from November 13, just before the temple is due to open again.

Sabarimala devotees believe letting women of menstruating age in goes against the wishes of the celibate deity the temple is devoted to.