A 19-year-old woman suspect has confessed her role in the foiled terror attempt to crash a Beijing-bound passenger aircraft from Urumqi recently, China said.

Guzalinur Turdi, an Uygur ethnic, carried a camouflaged destructive device on board the plane after deceiving the airport security personnel but failed (in her attempt), China's Ministry of Public Security said in a statement.

The woman and "other people involved" had been arrested by the police after the plot was unearthed on March 7, official Xinhua news agency said.

China had claimed that it had foiled a plot to crash China Southern Airlines aircraft after it took off from the restive Muslim-majority northwestern Xinjiang Uygur region with the killing of two terrorists in the same region in January.

Investigation showed that it was a "grave act of attempted sabotage instigated and conducted by Eastern Turkestan separatists from abroad," Wang Lequan, party chief of the Xinjiang Uygur Autonomous Region, said recently.

Earlier, China said that a 19-year-old woman and a man were detained by the police after the plane made an emergency landing at Lanzhou, capital of Gansu province two hours after taking off from Urumqi, capital of Xinjiang.

The third suspect, who was detained later, had admitted that he "masterminded, instigated and carried out the crime," it had said.

The airliner sources said crew members smelt gasoline on the woman who was leaving a toilet during the flight and then found a can containing the flammable liquid in a dustbin of the restroom.