Atomic-bomb survivor groups in Nagasaki and Hiroshima have condemned a recent remark by Russian President Vladimir Putin that he was ready to put his country's nuclear weapons on alert amid the crisis in Ukraine last year.

Five Nagasaki-based groups said Wednesday they will send a letter of protest to Russia demanding a retraction of the remark by Putin, which he made in a documentary that aired on Sunday.

The groups state in the letter, to be sent ahead of a review conference next month for the Nuclear Non-Proliferation Treaty, that Russia should play a leading role in working with other nuclear-armed nations to abolish such weapons.

They will also send a letter to Prime Minister Shinzo Abe requesting that he lodge a protest against Putin's remark.

Two groups in Hiroshima said they sent a protest letter to the Russian Embassy in Tokyo, criticizing Putin's comment as "an unforgivable act that attempts to lead the country to an advantageous position by threat."