Chinese police have taken a major shareholder of Shenzhen Airlines in for questioning.

"Li Zeyuan is now in the police office and we don't know when he will come out," says a Shenzhen Airlines official, who wishes to remain anonymous.

"The police didn't give us information" on why he is being questioned, says the official.

Shenzhen Airlines' day-to-day operations are unaffected by the move, adds the official.

In 2005, Li's company Shenzhen Huirun Investment put in a joint bid - with China's Bright Oceans Corporation - for Guangdong Development Bank Holding Group's 65% stake in Shenzhen Airlines.

They bid 2.72 billion yuan ($329 million), outbidding Air China which had been keen to take control of the airline. Air China owns 25% of Shenzhen Airlines.

Shenzhen Airlines is China's fifth largest carrier. It is primarily a domestic passenger airline but in recent years has moved onto short-haul international routes.

Source: Air Transport Intelligence news