China's state media said an attempt to crash a domestic flight last week was an act of organized terrorism, adding to signs of new volatility in the country's western regions.

China responded by stepping up security at its airports, on top of stringent security plans being put in place for the Olympic Games in August. Passengers are now banned from carrying any kind of liquid aboard domestic flights, and passenger and luggage searches are being increased.

Along with the ban on liquids, streamlined and VIP check-in procedures will be eliminated, checks of air cargo will be strengthened, and vehicles entering controlled airport space will be required to submit to searches, China's Civil Aviation Administration (CAAC) said in a notice posted on its Web site.

The Global Times newspaper said on March 13 that a 19-year-old woman from western China's Turkic Muslim Uighur minority group had been seized after trying to set a fire in a bathroom aboard the China Southern flight last week.

China's Foreign Ministry spokesman said no details were available because the incident was still being investigated.