Major newspapers railed against his decision to scrap plans to move an unpopular US airbase entirely off the island of Okinawa after months of dithering over the issue that angered close ally Washington.

"The governments recent disarray appears shameful," the top-selling Yomiuri Shimbun said in an editorial. "Needless to say, Prime Minister Hatoyama bears the greatest responsibility."

On his first visit to the sub-tropical island since he took office in September, Hatoyama on Tuesday apologised for his failure to meet his pledge to remove the US Marine Corps Air Station Futenma from Okinawa.

Hatoyama had long vowed to review an accord made in 2006 by previous governments in Tokyo and Washington under which the base should be moved from its current crowded urban location on Okinawa to a quieter coastal area.

However, a search for alternative sites in Japan has been met by more protests, leaving Hatoyama with few viable options ahead of a self-imposed May 31 deadline to resolve the matter.

"The prime minister has stated that he would stake his job on the resolution by the end of May. The words are grave," the Mainichi Shimbun said in an editorial.

"If he fails, it will be certain that his political responsibility should be rigorously examined."

The opposition camp stepped up pressure on Hatoyama to resign ahead of July elections for the upper house, where his Democratic Party of Japan does not enjoy a majority.

"Its a clear breach of promises and for people in Okinawa, its betrayal," said Sadakazu Tanigaki, president of the largest opposition Liberal Democratic Party.

"It is natural for the prime minister to resign" if he fails to resolve the issue by May 31, Tanigaki added.

The drawn-out dispute has angered residents of Okinawa, cost the centre-left leader much domestic support and strained ties with Japans key defence ally the United States, which wants the 2006 accord implemented.

Latest opinion polls in Japan have put support for Hatoyama and his cabinet at just over 20 percent, sharply down from 72 percent in September when he took office.

"Prime Minister Hatoyama cant help but lose his political influence further," said Shinichi Nishikawa, professor of politics at Meiji University in Tokyo.

"It would not be a surprise if calls for his resignation spread to his ruling coalition," Nishikawa said. "Even if he can survive for now, his resignation will be very likely after the election."

Hatoyama is reportedly proposing to follow the original plan in general, but some 1,000 US Marines and their helicopter operations would be moved to the remote island of Tokunoshima, 200 kilometres (120 miles) northeast of Okinawa.

Hatoyama plans to meet three mayors from Tokunoshima on Friday in Tokyo to ask them to back the proposal, but the mayors have already voiced strong opposition to hosting them.

Mizuho Fukushima, a Socialist leader in the ruling coalition, urged Hatoyama to reconsider his about-turn, saying: "He should accept Okinawas voice firmly."

The issue has stirred passions on Okinawa, site of some of World War IIs bloodiest battles, and still the host of more than half the 47,000 US troops stationed in Japan under a post-war security treaty.