From July 20, passengers have to undergo a security check before entering more than 20 major airports across the country, the Civil Aviation Administration of China (CAAC) said Monday.

The special measure is aimed at raising the security level at the airports and preventing anyone from carrying explosives, inflammables or other materials that can be used to disrupt the Beijing Olympic Games, the CAAC said.

Suspects will have to go through thorough security checks, and people caught carrying such materials will be dealt with strictly in accordance with the law.

The new security checks will be in addition to the normal ones, mandatory for every passenger.

It means people wishing to see off their relatives and friends inside the airport terminal buildings will also have to go through security checks.

The measure will be in force at the six mainland cities hosting the Olympic events, their "alternative airports" and all those in the Xinjiang Uygur and the Tibet autonomous regions.

Besides Beijing's Capital International Airport, the measure will be enforced in Shanghai's Pudong and Hongqiao, and Qingdao, Tianjin, Shenyang, and Qinhuangdao airports, and their "alternatives" in Shijiazhuang, Taiyuan, Jinan, Hangzhou, Nanjing, Hefei, Changchun, Harbin, Dalian and Hohhot.

Xinjiang has 11 airports, Urumqi, Hami, Korla, Kuqa, Hetan, Kashi (Kashgar), Aksu, Yining, Karamay, Fuyun, and Altay. Tibet has at least two civilian airports, with one about 75 km away from the regional capital of Lhasa.

The CAAC has already banned liquid and gel in any form from being carried by passengers. It has also banned lighters and matches in hand luggage and checked-in baggage both.

Many other airports, such as Kunming and Lijiang in Yunnan province, have already tightened security measures. If security officers think it necessary, they insist on making passengers take off their shoes and belts, open their suitcases and even put their laptops through special tests.

Will the extra security checks inconvenience passengers and cause unnecessary delays? To avoid hassles, the CAAC has urged passengers to reach the airports a bit earlier than usual.