SRINAGAR, India, Nov 11 (Reuters) - Three policemen were killed and six were wounded on Monday when their vehicle ran over and exploded a landmine planted by suspected militants in Indian-ruled Kashmir, police said.

It was the biggest attack on security forces in the revolt-racked region since Mufti Mohammad Syed, a regional leader, took over this month as the new chief minister of Jammu and Kashmir.

"An IED (Improved Explosive Device) planted by militants went off near Ramsoo when a security vehicle passed that way. Three security personnel were killed and half a dozen were wounded in the explosion," a police official told Reuters.

Ramsoo lies in Doda district, southeast of Srinagar, the summer capital of the Himalayan state. No militant group has claimed responsibility for the attack.

Security forces have launched search operations in the area, the official added.

Nearly a dozen militant groups are fighting New Delhi's rule in India's only Muslim-majority state, where more than 35,000 people have died in 13 years of fighting.