Security at China's airports has been ramped up ahead of the Beijing Olympics amid fears of terrorist attacks and social unrest, causing delays for passengers.

Passengers reported delays and missed flights at Beijing and Shanghai airports as baggage checks were stepped up.

China's aviation administration announced last week that it would ban passengers from carrying liquids aboard flights and began implementing the restrictions over the weekend, causing some people to miss their flights, travelers said.

The ban comes after Chinese authorities said an alleged Muslim terrorist tried to blow up a plane with soft drink cans containing petrol on a flight from China's Xinjiang region to Beijing this month.