By Nobuhiro Kubo

TOKYO, Nov 27 (Reuters) - Japanese travellers flying through China's new air defense zone on Wednesday said they supported a government-backed decision by Japan's main carriers to defy a Chinese demand for flight plans, with most unfazed by any potential risk.

China published coordinates for an East China Sea Air Defense Identification Zone over the weekend and warned it would take "defensive emergency measures" against aircraft that failed to identify themselves properly in the airspace.

The zone covers a large part of the East China Sea, including small uninhabited islands at the centre of a bitter territorial dispute between Beijing and Tokyo.

"It's unsettling to hear the airlines are not filing flight plans, but I understand the Japanese government telling them not to," said Hiroko Niizuma, 36, at Tokyo's Haneda airport before boarding a flight operated by ANA Holdings to Taiwan, where she works as a language teacher.

"Not saying anything would be to acknowledge the Chinese action."

ANA and Japan Airlines on Wednesday stopped sending Chinese authorities their flight plans for routes to Taiwan and other destinations that pass through the zone.

The carriers had been handing over the information since Saturday, but changed their minds after Japan's government told them it would ensure the safety of their flights, a spokesman from JAL told Reuters.

The government, according to the airlines, said it had won an assurance from China that its aim was not to restrict commercial flights, but did not elaborate on how it would guarantee the security of their aircraft.

The Japanese carriers posted a notice of the change on their websites, although passengers said they had not been contacted directly about the revision.

"There was no notification from the travel company or the airline, but I am not particularly concerned," said Norikazu Koizumi, 42, a transport company employee readying to board the same ANA flight at Haneda. "I agree with the Japanese government's action to stop the flight plans from being filed."

By demanding that airlines file flight plans through the zone or risk being intercepted by military jets, China is effectively forcing carriers to acknowledge its authority over a zone about two-thirds the size of Britain.

Other airlines in Asia have said they would comply with the Chinese demand.

JAL and ANA operate about 30 flights a day through the zone, mostly to Taiwan and Hong Kong, with flights to Bangkok and Singapore sometimes diverted through the area depending on weather conditions.

"I think what China has done is outrageous," said Hiroshi Hisatomi, 67, as he readied for the ANA Taiwan flight at the start of a vacation with his wife. "I don't think anything will happen and have no intention of changing my travel plans."