The mayors of two cities devastated by U.S. atomic bombs in World War II urged the central government Friday to sign and ratify a U.N treaty banning nuclear weapons set to enter into force in January.

"A recognition that nuclear weapons are an absolute evil has spread in the world," Hiroshima Mayor Kazumi Matsui said at the outset of his meeting at the Foreign Ministry with Eiichiro Washio, senior vice foreign minister, also attended by Nagasaki Mayor Tomihisa Taue.

In the meeting, the mayors presented Washio with a letter addressed to Foreign Minister Toshimitsu Motegi, requesting the government to attend a meeting of the member states of the Treaty on the Prohibition of Nuclear Weapons as an observer if it cannot immediately sign the pact.