The search for the Nuri helicopter that went missing yesterday afternoon soon after taking off from Miri airport is being classified as a highly secret 'military operation', according to a source.

The source also told malaysiakini that there is reason to believe that the 10 military personnel on board are well trained and capable of taking care of their needs, as the Nuri is a military aircraft that carries food rations and survival equipment.

Until anything else is known to the contrary, the chopper is still classified as "missing", the source said.

Meanwhile, the police air unit and 30 elite police commandoes from the Tiger Platoon are on standby in Miri to assist with search and rescue operations

"They are prepared for deployment in case our services are required," a senior police officer told reporters.

The Royal Malaysian Air Force (RMAF) Nuri went missing 15 minutes after take-off, en route to Ba'Kelalan - the same highland village that was the destination of the Hornbill Skyways Bell 206 helicopter which crashed on July 12, killing all seven on board.

The Nuri - from the RMAF 7th Squadron - was believed to be carrying two pilots, and three RMAF air quartermasters and five soldiers from the Royal Malay Regiment. It was also carrying supplies to the regiment's 20th Battalion.

The soldiers were to have relieved those on surveillance duty at the Sarawak-Kalimantan border post. However, the chopper did not arrive at its destination as scheduled, at 3.20pm yesterday.

The Star , quoting a source, said the chopper reportedly last made contact with the control tower while it was flying over the Mulu National Park near Long Seridan a sparsely populated remote settlement halfway between Miri and Bario.

The news report also said that, at about 7pm yesterday, several RMAF helicopters were seen taking off from Miri airport. Bario is about 400km from Miri, while Ba'Kelalan is about 70km north of Bario.

In Kuala Terengganu yesterday, Deputy Prime Minister and Defence Minister Najib Abdul Razak said the control tower in Kota Kinabalu failed to trace the helicopter's radio signals and that a C130 Hercules had been sent to check on this along the route.

JIMMY TEOH is malaysiakini's Sarawak-based stringer