Twenty-nine Border Security Force personnel and their family members were killed when the bus they were travelling in hit an improvised explosive device on the strategic Jammu-Srinagar highway on Sunday morning.

Nine were wounded in the blast, which took place near Gulabbagh, 80km from Srinagar in south Kashmir's Anantnag district.

The BSF men were going on leave with their families.

The Hizbul Mujahideen claimed responsibility for the blast.

The bus was part of a convoy, which was heavily guarded with a 'road opening party' deployed to clear the highway of IEDs.

"We have recovered bodies of 17 troopers and 12 of their family members," said Inspector General of Police (Kashmir range) K Rajendra.

"Among the dead are... six ladies, four children and two other relatives," Rajendra said. "Their bodies have been brought to Srinagar."

There were forty people in the bus, which caught fire after hitting the IED.

The bus was so mangled that rescue teams had to use gas torches to cut the metal and bring out the dead and injured.

Authorities pressed into service army helicopters for the rescue operation.

The injured, said to be in critical condition, were taken to a hospital in Srinagar for treatment.

Four of the injured were civilians travelling in a minibus that was passing by.

Soldiers with metal detectors scanned the highway for any other IEDs.

The highway is used to take supplies to the troops deployed inside the valley.