Traffic resumed today after the leak was repaired Chinese railway officials said. At least 20 trains were delayed because of the leak.
The leak was discovered around noon in a tunnel along the Beijing-Guangzhou high-speed railway, according to a statement issued by the Wuhan Railway Bureau.
The tunnel connects the cities of Changsha and Miluo in central China's Hunan Province, state run Xinhua news agency reported.
The Beijing-Guangzhou line, which links the Chinese capital and the southern metropolis of Guangzhou over a total distance of 2,298 km, went into operation on December 26 last year.