China called Wednesday for "patience" with a flagship high-speed rail link between Beijing and Shanghai as passengers suffered fresh delays on the newly opened line.

The official Xinhua news agency said people should be "tolerant" of problems with the trains after delays caused by power outages on Sunday and Tuesday sparked a slew of criticism online and in the Chinese media.

"It is lack of confidence if we immediately get suspicious of the high-speed rail and hype it up to attract attention whenever a glitch or accident happens," Xinhua said in a commentary.

"It also harms the national interests - you can imagine who would laugh quietly on the side," it said, in an apparent reference to foreign competitors of China's high-speed rail developers.

On Wednesday, the Beijing railway bureau said a train heading from Shanghai to Beijing had broken down at a station in the eastern province of Jiangsu, delaying passengers by more than two hours.

On Tuesday, 29 trains were delayed due to a power failure, after around a dozen were halted for about 90 minutes on Sunday for the same reason.

Chinese Premier Wen Jiabao formally opened the $33 billion line, which halves the rail journey time between the two Chinese cities to five hours, on June 30 - the eve of celebrations to mark the 90th birthday of China's Communist Party.

However, the huge investment in the new link has made the sector a hotbed for corruption. China's state auditor has said construction companies and individuals last year siphoned off 187 million yuan ($29 million) from the project.

The revelation followed the February sacking of former railways minister Liu Zhijun, who allegedly took more than 800 million yuan in kickbacks over several years on contracts linked to China's high-speed network.