Osaka Mayor Toru Hashimoto, coleader of Nippon Ishin no Kai (Japan Restoration Party), criticized on Tuesday a proposal by Sakai Mayor Osami Takeyama to hold a city referendum on participating in an integrated Osaka, calling it nonsense and a political stunt.

"Ridiculous. What's going to happen if you hold a referendum at a stage when the details of the integration are not yet understood? This is being done for his political campaign," Hashimoto said.

Takeyama, mayor of Osaka Prefecture's second-largest city, is opposed to a plan backed by Hashimoto and his Osaka political group, Osaka Ishin no Kai (One Osaka), to merge all of the prefecture's cities to create a government entity along the lines of Tokyo's 23 wards.