Japan is collecting more tax revenue from Australian liquefied natural gas than the federal government, heightening concern the public is missing out on the wealth benefits of the gas export boom.

Japan, which is the single-biggest buyer of Australian LNG at 30 million tonnes a year, levies an import tax that will deliver $2.9 billion to its national coffers over the next four years, according to research conducted by the International Transport Workers' Federation, a member of the Tax Justice Network.

By comparison, Australia will not receive a cent in petroleum resource rent tax from gas projects operating in federal waters over the same period.

The $800-million-a year PRRT collected in Australia - which has halved over recent years - is largely paid by established oil operations in Bass Strait rather than LNG producers.