A group of Osaka legislators tasked with discussing municipal integration formally approved a plan Tuesday that would merge the city's 24 wards into five semi-autonomous zones, each with its own elected head.

The decision sets the stage for approval by the full municipal assembly next month, which will result in a public referendum to be held May 17.

It came after Komeito, which works with Osaka Mayor Toru Hashimoto's Osaka Ishin no Kai (One Osaka) in the assembly to form a majority, dropped its opposition to a public referendum.