Li Changjin, chairman of China Railway Group Ltd,  also said that it was difficult for China to complete this year's plan for railway infrastructure investment.

Separately, the official Xinhua news agency on Saturday reported Beijing vice mayor Chen Gang as saying city authorities would spend 100 billion yuan on adding an extra 200 kilometres of capacity to the capital's subway network to take its total size to 660 kms. No schedule for the Beijing works was given.

Both men were speaking on the sidelines of China's Communist Party congress which is meeting to choose new leaders.

To support the slackening domestic economy, China has raised its planned total railway investment by 20 billion yuan to 630 billion yuan for 2012, the country's Ministry of Railways said in October.

Beijing has also approved 25 rail projects that could be worth more than 700 billion yuan as part of measures to support the broader economy, currently grappling with its slackest period of growth since early 2009.

The government said on Wednesday it would increase state spending and offer tax breaks to quicken the development of the country's urban public transport system.