SASEBO NAVAL BASE, Japan — Nearly two months after learning a U.S. submarine leaked minute amounts of radiation in its harbor, the city of Sasebo said it hopes to persuade the U.S. Navy this week to cooperate in local safeguards against accidents involving nuclear-powered vessels.

Sasebo Mayor Norio Tomonaga was scheduled to meet Thursday with Commander Naval Forces Japan and U.S. Embassy officials to urge participation in an annual nuclear disaster drill, according to the city’s base affairs official, Setsuo Kuga.

But officials at Sasebo Naval Base said Tuesday that participation is unlikely. The Navy has steadfastly stuck to its position that its nuclear vessels are safe enough that accident drills with Japan are not needed.

However, in advance of the nuclear-powered aircraft carrier USS George Washington’s recent arrival to Yokosuka Naval Base, the Navy participated in a nuclear drill with the city of Yokosuka in November.

Concern has ratcheted up in Sasebo after it was discovered the USS Houston seeped small amounts of radioactive water during visits to Sasebo in March and April — amounts Secretary of the Navy Donald Winter called "undetectable by any mechanism" while visiting the base last week. The sub also leaked in Yokosuka, Okinawa and Guam.

"Sasebo city has no nuclear power facility. If a disaster were to happen, it can’t be from anyone but from the U.S. Navy," Kuga said. "Even the safety of the ships is written in the fact sheets. The probability is not zero as long as nuclear ships visit."

The city is planning to conduct the nuclear disaster preparedness drill in late January and wants the Navy’s participation to establish an initial accident response system, Kuga said.

During a meeting with the Sasebo mayor last week, base commander Capt. Francis Martin said he doubted the Navy would reverse its position, base officials said.

"We advised him that the request would be staffed and forwarded to CNFJ but that we expected that our policy of not participating in this particular drill would not change," base spokesman Chuck Howard said in an e-mail response Tuesday. "We told him that the base has a track record of cooperation and participation with the city in the area of disaster preparedness that we are committed to continuing."

The Navy in Sasebo has participated in five joint disaster and fire drills with the city since May 2005, though none of those drills involved nuclear vessel scenarios, according to the base.

In August, the city assembly unanimously passed a resolution calling on the U.S. Navy to conduct a thorough investigation of the USS Houston leak and start participating in the city’s annual nuclear safety drill.

The Houston leak was discovered when about a gallon of water containing trace levels of radioactivity spilled onto a sailor July 17 while the sub was in dry dock in Hawaii.

After about two weeks of investigating, the U.S. announced to the Japanese government that the sub had leaked for two years and discharged tiny amounts of radioactive water at three ports in the country.

Sasebo leaders have criticized the national government for a one-day delay in notifying the city of the leak.