Global natural gas inventories are swelling as demand for liquefied natural gas (LNG) slowly recovers. And as the economy recovers, fears of a second outbreak add to the cautious mood.

Storage tanks in countries such as Japan, South Korea and Europe are full and dozens of liquefied natural gas tankers are idle, trade and shipping sources said.

Rebecca Mopler, an analyst with Kpler, a data intelligence firm, said: "It's a good idea to get into the game. Mr Jia said 27 tankers full of liquefied natural gas had been marked as "floating", with eight indicating their destination was Japan. According to Kpler, if a boat is on the water for more than five days, it will be marked "floating."

Demand for natural gas in Japan, the country's largest importer of liquefied natural gas, has been weak as the outbreak has forced hotels and restaurants to close and factories to suspend operations. In May, gas sales in the commercial sector were down 50% from a year earlier, while those in the industrial sector were down 20-30%.

Japan declared a state of emergency in early April that lasted until late May, when monthly LNG imports hit their lowest level in a decade.

Korea National Gas Corp, The country's largest LNG importer, has delayed several shipments to the second half of the year as it deals with high inventories, sources told Reuters.

European gas inventories have also been at record levels after a mild winter.

"Storage capacity in north-west Europe is expected to reach peak capacity by the end of the injection season and is expected to take some time in August," said analysts at Simpson Spencer Young, a shipbroker.