The military has already expressed concern that India may be trying to move past the line of control which divides the Pakistan and Indian forces.

The BBC's Owen Bennett-Jones: "Pakistan trying to assess India's intentions"

Army spokesman Brigadier Rashid Qureshi said: "A few bombs have landed on our side of the line of control - this makes matters, very very serious.

"The Pakistan armed forces reserve the right to retaliate by whatever means are considered appropriate," he said.

Protest to be lodged

The responsibility for any escalation would "squarely rest on India and its armed forces", he added.

Mr Qureshi added that Pakistan had taken "very serious notice" of the situation and would lodge a protest with India.

Paul Danahar reports from Delhi: "Strikes are inside India"

India has denied that any bombs fell on the Pakistan side of the border in Wednesday's attack.

In recent days the Pakistan army says it has noticed a concentration of Indian troops and aircraft in Kashmir, and warned them not to cross the line.

Correspondents say there has been no sign that the Indian forces have moved.

India says it is trying to remove militants who moved into Indian-controlled Kashmir from Pakistan and took territory near the town of Kargil.

Pakistan says that while it offers moral support to the militants, it does not give them logistical back-up.

Call for calm

The foreign minister of Pakistan has called for restraint.

Sartaj Aziz told a local news agency he did not know why India had decided to attack Kashmir and the action should not be escalated.

"There has to be restraint from both sides," he said. "We don't know why they are escalating the situation."

But he warned: "If they attack our positions, we will defend ourselves."