Turkish politician in air crash

Muhsin Yazicioglu is one of six people missing

The chairman of Turkey's ultra-nationalist Grand Unity Party is missing after the helicopter he was travelling in crashed on Wednesday.

Hundreds of rescue workers have joined the search for Muhsin Yazicioglu, the pilot and four further passengers.

Turkish TV channels broadcast a phone call reported to be from one of the passengers saying that "everybody else on the helicopter seems to be dead".

Continuing bad weather conditions are slowing down the search efforts.

Mr Yazicioglu was returning from a political rally ahead of Sunday's local election when his helicopter ran into trouble in the mountainous area of Kahramanmaras province at 1500 local time (1300 GMT).

Call for help

Turkish TV channels have played a recording of a phone call they say one of the passengers made shortly after the crash.

In it, Ismail Gunes, a reporter for the IHA news agency, talks about a snowstorm and fog. He goes on to say that he fears he is the only survivor.

The Transportation Minister, Binali Yildirim, told the Anatolian news agency that they had "received signals from mobile phones of the pilot and the passengers". He said efforts were under way to locate the co-ordinates of their whereabouts.

Some members of Mr Yazicioglu's party have protested outside the office of the Interior Minister over the failure to locate the crash site almost 24 hours after the accident.

Hundreds of volunteers as well as police are taking part in the search and rescue efforts, which officials say are being hampered by the continuing harsh weather conditions.

A number of political parties, including the governing Justice and Development Party (AKP) and the opposition Republican People's Party, have cancelled their election rallies scheduled for Thursday.

The BBP won less than 1% of the vote at the last election. It combines a far-right political ideology with strong Islamic beliefs, says the BBC's Sarah Rainsford in Istanbul.