At the ceremony, Kosor said that this investment would pave the way for a different, better life for local inhabitants and for new investments in the local economy.
The project is about the construction of a 8.7-kilometre-long embankment on the right bank of the Neretva river in the residential area of Jerkovac.
Apart from the embankment, the project includes pump stations and drainage channels.
The flood-protection system is to be constructed by the Split-based Konstruktor-Inzenjering company by October 2014.
Metkovic has been hit by flooding several times in recent years.
Earlier in the day, Kosor also inaugurated HRK 25-million works on the construction of a building to house the municipal court in that town.
(EUR 1 = HRK 7.4)