TOKYO (AP) Japan's foreign minister said Monday that Tokyo should honor its agreement to find a new location for a major U.S. Marine base, but he and the prime minister said they were still seeking options on where it should go.

Japan and the U.S. agreed in 2006 to relocate Marine Corps Air Station Futenma to a site farther north on Okinawa in the city of Nago, but Prime Minister Yukio Hatoyama has put the deal on hold and indicated the relocation site could be changed.

''It would be extremely difficult to scrap the U.S. military realignment agreement that has been already reached,'' Foreign Minister Katsuya Okada said after a two-day trip to Okinawa, adding the top priority is to move the base out of its current location in a crowded city on the southern island.

Okinawans have long complained about noise, pollution and crime linked to U.S. troops. Many of them want the base moved off the island entirely and thousands protested over the issue earlier this month.

Okada has repeatedly suggested the base's functions be moved to nearby Kadena Air Base, not Nago, a counterproposal that has already been rejected by Washington and is opposed by the local mayor.

During his visit to Okinawa, Okada appeared to back off on that idea, agreeing a move to Kadena would be acceptable only if noise-reduction measures were taken.

On Monday, Hatoyama cast further doubt on the deal, saying an upcoming review of the agreement and other aspects of the U.S. military's presence in the country by a bilateral task force will not be swayed by the 2006 pact.

''If our review is merely aimed at making a decision confirming the agreement, it's meaningless,'' Hatoyama told reporters in Tokyo. ''If we already have an answer, we don't need to hold talks.''

The Futenma relocation is the central component of a major realignment of the 47,000 U.S. troops in Japan most of them on Okinawa.

U.S. officials have pressed Japan to stick to the original agreement. President Barack Obama said during a visit to Tokyo last week the two sides should work ''expeditiously'' toward a resolution.

Tensions on Okinawa over the huge U.S. military presence go back decades. The 1995 rape of a 12-year-old girl by three American servicemen ignited furor and calls for a reduction of U.S. bases on the island.