New Delhi, Jun 25 (IANS): A newly-acquired Indian Air Force (IAF) Mi-17 V5 helicopter crashed while engaged on a rescue mission in Uttarakhand Tuesday killing 20 people, a top official engaged in the relief operations said. The IAF, however, put the toll at eight, including the chopper's five crew members. Prime Minister Manmohan Singh expressed shock over the accident and expressed his condolences to bereaved families.

The crash also claimed the lives of nine personnel of the National Disaster Response Force (NDRF) and six of the Indo-Tibetan Border Police (ITBP), National Disaster Management Authority vice chairman Shashidhar Reddy told IANS.

The helicopter, on a rescue mission from Gauchar to Guptkashi and Kedarnath, crashed north of Gaurikund on the return leg from Kedarnath, an IAF statement said.

"The eight persons onboard, including five crew members, sustained fatal injuries," the statement said.

"While a Court of Inquiry has been ordered to investigate into the accident, the IAF's rescue operations continue," the statement added.

Indian Air Force chief N.A.K Browne had Monday assured people still trapped in flood-affected regions of Uttarakhand that his force will continue to fly helicopters till each one of them was evacuated.

"Our helicopter rotors will not stop churning till such time we get each one of you out. Do not lose hope and hang in there," Browne said in a message to the stranded people who need to be air-lifted.

In his message, the prime minister said that the forces were are conducting a heroic task in rescue and relief work in Uttarakhand.

"This accident during relief operations has come as a huge shock to me. My heart goes out to the families of those who have lost their lives," he said.

"The nation mourns with me the loss of our heroes whose selfless work has saved thousands of lives. Continuing their work would be the best homage to them," he said.

Indian Air Force Tuesday conducted 53 sorties to air evacuate 535 stranded people.

Till Monday, the IAF had airlifted 10,731 people, flying 1,163 sorties and dropping/landing 184,262 kg of relief material and equipment.