Australia's Qantas airline has cancelled five return A380 superjumbo flights between its new overseas hub in Dubai and London because of weak seasonal demand.

The cancelled flights are over the next two months, said a Sydney Morning Herald report.

Qantas will reduce the number of return flights between Dubai and London's Heathrow Airport from two to one on October 14 and 17, and on November 12, 15, and 20. Passengers on the cancelled flights will be put on Qantas' other A380 service or an Emirates flight.

Qantas had cancelled three return superjumbo flights between Dubai and London in May, citing a slowdown in demand during the northern winter, the report said.

The airline has emphasised that it will increase and reduce capacity on routes where it makes sense, pointing to a recent boost to flights between Melbourne and the US.

Qantas began flying via Dubai to Europe - instead of via Singapore - in March last year when it launched its extensive alliance with Emirates.

Qantas' pre-tax losses from its international division widened to almost half a billion dollars last financial year, from $246 million in the  previous year, the report said.