A Senate committee is seeking to block the relocation of U.S. military bases and personnel in east Asia, a plan it sees as too costly and impractical, the panel's chairman said Friday.

Legislation backed by the Senate Armed Services Committee would prohibit funding to relocate the U.S. Marine base in the southern Japanese island of Okinawa. It also would suspend plans to relocate the families of thousands of U.S. service members to South Korea.

Committee chairman Sen. Carl Levin, D-Mich., called the plans "unsustainable and incredibly expensive," and his committee wants more studies conducted before Congress approves money for the move.

The panel's proposals are part of a $683 billion defense spending bill that has to clear several legislative hurdles. The committee's move follows calls last month from Levin and two other prominent senators — Jim Webb, D-Virginia and John McCain, R-Va. — for the Defense Department to re-examine the plans for east Asia.

"The major step we have taken is to put all these changes on hold," Levin told reporters in a conference call Friday. "We are not withdrawing our presence (from east Asia). We are trying to streamline it ... in a way that's honest and sustainable."

It comes ahead of a high-level U.S.-Japan security meeting in Washington next week. Secretary of State Hillary Rodham Clinton and Secretary of Defense Robert Gates will host Japanese Foreign Minister Takeaki Matsumoto and Japanese Defense Minister Toshimi Kitazawa on Tuesday. Among the issues they will discuss are missile defense and the realignment of U.S. forces in Okinawa, the State Department said.

Levin singled out as "unachievable" the current plans for relocating U.S. forces in Okinawa, which hosts more than half the 47,000 U.S. troops in Japan.

The issue is a politically charged one. Although Japan is a staunch U.S. ally, many of the islanders resent the presence of the American forces because of noise, pollution and crime associated with the military bases. A 2006 U.S.-Japan agreement aimed at decreasing America's military footprint remains in limbo as still requires local approval.

Under the agreement, Marine Corps Air Station Futenma, located in a heavily populated southern part of Okinawa, would be closed and its air operations shifted to a less crowded northern area at Camp Schwab. Some 8,000 Marines would also be shifted to the U.S. Pacific territory of Guam by 2014. Japan would foot much of the multibillion relocation bill.

The Senate bill would require the Defense Department to study the feasibility of relocating Marine Corps air units to Chadian Air Base in another part of the island rather than build a costly new facility at Camp Schwa. It has been suggested that Air Force units currently at Kadena could be shifted elsewhere, possibly to an underused air base on Guam.

The bill also calls for a suspension of plans to relocate up to 12,000 families to live with service members in South Korea, where there are 28,000 U.S. forces, pending review of costs and alternatives. Some 1,400 families already live in-country.

Other than the cost, critics have questioned the relocation plans because of the uncertain security situation across the heavily militarized frontier in North Korea.

The U.S. troop presence is a legacy of the 1950-53 Korean War which ended with an armistice rather than a peace treaty.

Asked about the Senate panel's proposals, Defense Department spokeswoman Cmdr. Leslie Hull-Ryde said the military remained committed to its current agreements and policies that had been carefully developed over many years in close consultation with U.S. allies and within the U.S. government, including Congress.