TOKYO - Japan's embattled defence minister resigned Tuesday following his comments suggesting the 1945 U.S. atomic bombings of Hiroshima and Nagasaki were inevitable.

Fumio Kyuma had come under intense criticism from A-bomb survivors, opposition legislators and fellow members of the cabinet following the comments over the weekend.

"I told Prime Minister (Shinzo)/> Abe I would take responsibility and resign. The prime minister said it's a shame...but said he accepted it,'' Kyuma said.

Kyuma ignited a political furore less than a month before parliamentary elections when he said Saturday the atomic bombings of Hiroshima and his native Nagasaki were an inevitable way of ending the Second World War.

The statement contradicted the Japanese stance, fiercely guarded by survivors and their supporters, that the use of nuclear weapons is never justified. A ban on possession of such weapons is a pillar of Japan's postwar pacifist regime.

Earlier Tuesday, Nagasaki's mayor made an official protest in Tokyo.

"That comment tramples on the feelings of the A-bomb victims and as a target of the bomb, Nagasaki certainly cannot let this go by,'' Nagasaki Mayor Tomihisa Taue wrote in a letter handed over to Kyuma over Tuesday morning.

"I truly apologize for having troubled and caused worry to the people of Nagasaki,'' Kyuma said.

The bomb comment from the gaffe-prone Kyuma has hit Abe's increasingly unpopular government at a sensitive time, coming just a few weeks before July 29 elections for the upper house of parliament.

Kyuma's repeated apologies and Abe's reprimand of his defence chief have failed to quell the furore, which on Tuesday sparked further public criticism among Abe's own ministers, several of whom called the comment inexcusable.

The opposition had been preparing to submit a formal request for Kyuma's resignation later Tuesday and opposition leaders claimed Abe shared the blame for the gaffe.

At a speech in Chiba outside of Tokyo on Saturday, Kyuma triggered the scandal by suggesting the bombs were an inevitable way of ending the war.

"I understand that the bombings ended the war and I think that it couldn't be helped,'' he said.

Kyuma -- who represents Nagasaki in the lower house -- said the U.S. atomic bombings caused great suffering in the city but otherwise Japan would have kept fighting and ended up losing a greater part of its northern territory to the Soviet Union, which invaded Manchuria on the day Nagasaki was bombed.

Abe has struggled to control the political damage. He reprimanded Kyuma on Monday and asked him to refrain from making similar remarks in the future but did not publicly call for Kyuma to resign.

Top government spokesman Yasuhisa Shiozaki dismissed reporters' questions about a possible resignation, saying Tuesday that Kyuma has already explained and apologized for his remarks and been "sternly warned'' by the prime minister over them.

On Aug. 6, 1945, the United States dropped a bomb nicknamed "Little Boy'' on Hiroshima, killing at least 140,000 people in the world's first atomic bomb attack. Three days later it dropped another atomic bomb, "Fat Man,'' on Nagasaki where about 74,000 are estimated to have been killed.

Japan, which attacked the United States at Pearl Harbor in 1941, surrendered Aug. 15, 1945.

In January, Kyuma raised eyebrows in Washington by calling the U.S. decision to invade Iraq a "mistake'' because it was based on the false premise that the late president Saddam Hussein possessed weapons of mass destruction.

Japan and the United States are close military allies and Japan hosts some 50,000 U.S. troops under a security treaty.