Patrol units with sniffer dogs are deployed at entrances to the subway in Shanghai as part of enhanced security measures before and during the Expo. [China Daily]

China is confident of hosting a safe and successful World Expo, Shanghai's top leader has said in the aftermath of serial suicide bombings in Russia which have jolted the world.

With 30 days to go before the grand opening of the gala, Shanghai Party chief Yu Zhengsheng said the city can ensure the security of the 184-day event with the key being mobilization of people and careful implementation of plans.

"All the infrastructure will be completed in time; all measures on security, traffic and publicity have been taken, and residents have high expectations of the Expo - all of which show that we are ready," he said.

"I am confident that with the help of the public, we will do an excellent job on security," he added.

Security has become a paramount issue following Monday's double suicide bombings in Moscow, which killed 39. Another two suicide bombings in Russia's North Caucasus region on Wednesday killed at least 12.

Major Chinese cities have stepped up security checks at subway stations while some propose upgrading checks at bus stations.

The final touches being made to the interior of the Australian pavillion on Tuesday. [China Daily]

Beijing on Tuesday beefed up security in the city's metro system.

Fu Zhenghua, director of the Beijing public securit bureau, said police patrols with sniffer dogs were increased at metro stations, where they will make more frequent checks.

Many believe the Expo faces tougher security challenges compared to the 2008 Beijing Olympic Games due to the six-month duration and huge number of visitors, estimated at 70 million.

Pan Guang, an expert on anti-terror affairs at the Shanghai Academy of Social Sciences, said for any big event, vigilance tends to wane as it draws on.

Li Wei, director of the anti-terrorism research center at the China Institute of Contemporary International Relations, said security threats could come from anywhere, such as from "East Turkistan" terrorist organizations seeking Xinjiang "independence".

Shanghai has taken such measures as extending the X-ray scanning of passengers' hand luggage to all metro stations.

City officials are also hoping to close a deal with Swedish security services provider Securitas AB.

Taking a cue from Beijing's preparations for the 2008 Games, Shanghai has called on 1 million volunteers - many of them retirees - to patrol streets and detect any security hazards.

The combination of professional anti-terrorism forces and the public "forms an effective anti-terrorism module", Wu Heping, the spokesman for the Ministry of Public Security, told a Tuesday news briefing.

"In general, China's security situation is stable," he said.

Yu said the focus in the coming month is the six trial runs which will be staged in and around the Expo site, each involving 500,000 people.

He warned the public that visiting the Expo will not be a picnic because of the expected huge influx of visitors. An average of 400,000 people are expected to visit the Expo daily between May 1 and Oct 31.

More than 15 million visited the Aichi Expo in Japan five years ago, with each pavilion taking up to four hours to visit.

Shanghai has come up with various measures to deal with the crowds expected to flood the Expo on weekends or holidays, Yu said.

For instance, individual visitors are encouraged to join group tours. The Labor Day holiday will also be extended by two days, from April 30 to May 4, Yu said. The measure is designed to help ease the travel crush during the period.

The opening of the Expo will include a 30-minute art performance, Yu said, after which the scene will shift to the Huangpu River - to highlight the identity and location of the host city - where fireworks, fountains, lighting displays and music shows will be staged. The entire ceremony will last for around one-and-half hours.