Although due to start commercial operations in late June, the Beijing-Shanghai high-speed railway still has some safety problems, senior railway officials said on Thursday.

Hu Yadong, vice-minister of railways, said illegal and unlicensed businesses, including manufacturers of inflammable and explosive goods, operate along the line. Also, there are blasting sites within a kilometer of the railway line and not enough traffic signs along it.

Large illegal buildings, the removal or destruction of security fences and people dredging sand or digging wells also pose dangers to the railway, Hu said.

According to Hu, some of these practices are considerably dangerous and will create "great hazards".

"The Beijing-Shanghai high-speed railway will undergo intensive safety inspections before it starts operating," said Ji Jialun, a professor at the Beijing Jiaotong University.

Ji said several teams of experts have been invited by the Ministry of Railways to check the potential hazards and then provide reports to railways authorities.

The State Administration of Work Safety also launched a special railway safety campaign, which runs from June 1 to July 31, to further guarantee the security of the rail line.

Wang Dexue, deputy director of the State Administration of Work Safety, said on Thursday that the high speed and the new technology used in the operation and management of the bullet trains increased the risks.

As "airliners on railway tracks", they are also vulnerable to attacks by extremists, Wang said.

The 1,218-kilometer Beijing-Shanghai high-speed railway, which links China's two biggest cities, has been undergoing a one-month trial operation to finalize preparation for commercial operations. It is expected to cut travel time between the cities to about five hours.

An inspection team of 30 Chinese engineering academicians and experts, which was recently invited by the Ministry of Railways to check the basic structure and operation of the line, confirmed that the railway is ready to be put into use.

Inspection results showed that the line's rail track, communications and power supply systems are reliable and have met requirements, Xinhua News Agency reported.

An officer with the Beijing railway security authority, who spoke on the condition of anonymity, confirmed that "there are actually some mines located near the high-speed railway lines," but refused to disclose how the authority will handle the security hazards.