The government and Mitsubishi Heavy Industries Ltd. are considering giving up on a nuclear project in Turkey amid ballooning costs, in a blow to Tokyo's efforts to boost growth through infrastructure exports, sources close to the matter said Thursday.

The parties have determined that costs to build four reactors and ensure their safety in the Black Sea coastal city of Sinop have increased to a level the Turkish government will not accept, raising the likelihood that the project will not be profitable, the sources said.

The project's expenses have ballooned to over ¥5 trillion ($44 billion), more than double the initial estimate, due partly to increased safety-related expenses following the 2011 triple core meltdown at the Fukushima No. 1 nuclear power plant, other sources said earlier.