© Russian Ministry of Emergencies
The rescue involves 435 people assisted by 88 units of hardware.
Rescuers vow to find helicopter that vanished in strong winds on 10 October.

There is still no trace of the missing Mi-8 helicopter that went missing Tyva Republic on 10 October with 12 people on board.

Emergency teams have scoured 36,562 kilometres in a huge operation that has involved aerial searches and interviews with more than 600 potential witnesses, including local hunters and fishermen in one of the remotest areas of Siberia.

'There is no set time limit on such search. It depends on weather conditions and other factors,' said the regional centre of the Emergencies Ministry, which has used thermal images from space in a bid to locate the missing helicopter and crew, to no avail.

'We are looking until we find. If an emergency happens in winter, high in the mountains, in several meters of snow, the search becomes incredibly complex.'

The statement acknowledged it maybe necessary to 'wait until spring'.

But hopes remains that some or all the lost men could be alive. 'Whether there is someone alive depends on many factors. There is no information what happened to the helicopter, and in which circumstances. Perhaps the people are all right, but they cannot get in touch. It is a matter of chance, it makes no sense to guess and compare this situation with others. Hopefully, these people are alive.'

The lack of a beacon from the helicopter is seen as a hopeful sign.

If the helicopter crashed, then there is a signal. It is not clear why beacon on missing helicopter did not work, maybe there was no hard fall. It is too early to draw any conclusions yet.'

Four aircraft were deployed on Monday, with 78 people and four vehicles.

On Sunday, more than 200 rescuers on snowmobiles examined more than 250 kilometres of mountainous terrain and taiga.

The rescue operation involves 435 people assisted by 88 units of hardware, not only from Tyva but from other regions as well.

Radio contact with the helicopter was lost when it was on the way between the communities of Sorug and Kyzyl, located 270 kilometres apart.