China's civil aviation authorities will tighten the regulation and guidance of international airports on COVID-19 epidemic containment measures after an airport in Nanjing, Jiangsu province reported cluster infections due to lax management, an official with the Civil Aviation Administration of China said.

The CAAC will intensify checks on international airports to make sure they strictly implement epidemic prevention and control regulations, CAAC official Han Guangzu said at a news conference on Wednesday.

All frontline airport workers will be required to take nucleic acid tests every other day and other workers should take tests twice a week, he said.

Service personnel for international and domestic flights are not allowed to mix, he added.

Wu Shiping, an official with the China State Railway Group, said railway stations across the country will continue to strictly follow epidemic prevention and control regulations of local governments and forbid people who do not meet the requirements from boarding trains.

The railway operator has suspended ticket sales from medium- and high-risk areas to Beijing and offered a free ticket return policy to discourage travel, he said.

Li Huaqiang, an official with the Ministry of Transport, said the ministry has taken different measures to prevent the transmission of COVID-19 through roads and waterways.

The ministry has increased the frequency of nucleic acid tests for frontline workers at highway and waterway ports. 438 foreign boats of 18 shipping companies have been suspended from docking at domestic ports as of Tuesday, he said.