SEOUL (AFP) - South Korean airlines on Thursday said they would comply with rules set by Beijing for its newly declared air defence zone over the East China Sea.

The move followed guidance from Seoul allowing airlines to choose if they would adhere - a policy regarded as tacit state approval - but is in breach of South Korea's official stance which rejects the new zone.

Last month China declared an Air Defence Identification Zone (ADIZ), which covers much of the East China Sea, and expects all aircraft passing through to provide a flight plan and identification details.

South Korea had defied this with military overflights and on Sunday responded by expanding its own zone, but the country's two major airliners have confirmed they are now providing information in line with Chinese requirements before traversing the area.

"We started submitting flight plans as of today," an Asiana spokeswoman said.

Korean Air is also complying, a company spokesman said.

South Korean Transportation Minister Suh Seoung Hwan on Wednesday told journalists it should be left to local airlines to decide whether to abide by China's new rules.

But he stressed there was no change to Seoul's official position that it rejects the China zone.

The zone covers a disputed South Korean-controlled rock - known as Ieodo in Seoul and Suyan in Beijing - that has long been a source of tension between the two countries.

Weeks after Beijing provoked regional fury by establishing the zone, South Korea on Sunday expanded its own, overlapping with the one announced by China.

China's ADIZ, which encompasses some areas currently controlled by South Korea or Japan, has drawn intense protests from the two neighbours and objections from key allies such as the United States.