SINGAPORE — Japan has condemned US President Donald Trump for comparing recent US strikes on Iran to the bombing of Hiroshima and Nagasaki that ended World War II.

"That hit ended the war," Trump told reporters on Wednesday. "I don't want to use an example of Hiroshima, I don't want to use an example of Nagasaki, but that was essentially the same thing."

About 140,000 people died when the US dropped atomic bombs on the two southern Japanese cities in August 1945. Survivors live with psychological trauma and heightened cancer risk to this day.

If Trump's comment "justifies the dropping of the atomic bomb, it is extremely regrettable for us as a city that was bombed," said Nagasaki Mayor Shiro Suzuki.

Trump's comments are "unacceptable", said Mimaki Toshiyuki, an atomic bomb survivor who co-chairs the Nobel Peace Prize-winning advocacy group Nihon Hidankyo, public broadcaster NHK reported.

"I'm really disappointed. All I have is anger," said another member of the group, Teruko Yokoyama, in a Kyodo News report.

Survivors of the atomic bomb attacks staged a protest in Hiroshima on Thursday, demanding Trump retract his statement.

Lawmakers in Hiroshima also passed a resolution on Thursday rejecting statements that justify the use of atomic bombs, and called for armed conflicts to be settled peacefully.

Asked if Tokyo would lodge a complaint over Trump's remarks, Chief Cabinet Secretary Hayashi Yoshimasa said that Japan has repeatedly expressed its position on atomic bombs to Washington.

Trump's comments on Wednesday came as he pushed back on a leaked intelligence report that said US strikes on Iran only set its nuclear programme back by a few months.

Trump had insisted that the strikes "obliterated" the program and set it back "decades" - a claim backed by CIA director John Ratcliffe.

Japan is the only country in the world to have been hit by a nuclear attack and the bombings of Hiroshima and Nagasaki still stir painful memories.

In Hiroshima, a peace flame that symbolises the country's opposition to nuclear weapons has been burning since the 1960s while a clock that counts the number of days since the world's last nuclear attack is displayed at the entrance of a war museum.

World leaders who visit Hiroshima are also asked to make paper cranes to affirm their commitment to peace. — BBC