The announcement came days after India and a major separatist group in the tea-and-timber rich state of Assam, which borders Bhutan, ended a six-week ceasefire.

Ten battalions comprising 10,000 troops will patrol the 380-kilometre (240-mile) border with Bhutan by year's end and another 2,000 troops in 2007, according to a federal home ministry official who declined to be named.

India already has around 5,000 troops posted along its remote northeastern border with Bhutan.

"The number of border posts is also being increased from 32 to 135 to make the security presence visible in the area," the official said.

Intelligence reports showed separatist guerrillas from Assam planned to set up new bases in the mainly Buddhist nation, the official said.

"We need to be vigilant as army operations are now on in Assam against Ulfa and the rebels might once again try to take shelter in Bhutan and hence the stepped-up security," the official said.

In 2003, the tiny Bhutanese military destroyed rebel camps including those of Assam's United Liberation Front of Asom (Ulfa), which had staged hit-and-run attacks on Indian targets from across the border.

The Buddhist nation has assured New Delhi that it will not give refuge to rebels fleeing India's northeast, a region racked by separatist insurgencies. It says it now has no Indian militants camps on its soil.

At least 30 rebel armies operating in northeast India use bases in neighbouring Bhutan, Bangladesh and Myanmar. Their demands range from autonomy to secession in conflicts that have killed more than 50,000 since India gained independence from Britain in 1947.