NARATHIWAT, Thailand: A massive roadside bomb killed three policemen in Thailand's restive south on Friday, an army spokesman said, a fortnight ahead of peace talks between Thai authorities and a rebel group.

The 90 kilogram (200 lbs) bomb, hidden at a footbridge in Ruso district of Narathiwat province, detonated as a local police patrol passed on a pick-up truck, killing the officers and destroying the vehicle.

Confirming the deaths, southern regional army spokesman Colonel Pramote Promin said the attack may have been carried out by rebels opposed to the opening of talks, which are set to be held in Malaysia on March 28.

"There are insurgents who do not agree with their leaders on joining the peace process and (therefore) try to incite more unrest," he said.

The Thai government has agreed to hold talks with Barisan Revolusi Nasional, which is part of a web of shadowy insurgent groups in the south.

A stubborn insurgency seeking greater autonomy has raged across several provinces in the south of Thailand bordering Malaysia for nine years -- with near-daily shootings and bombings.

Paradorn Pattanatabut, the head of Thailand's National Security Council, said a preliminary meeting with the rebel group was held on March 5 on the "conditions" for the talks, but more substantive dialogue would begin with the one-day exchange in Malaysia later this month.