Nippon Telegraph & Telephone Corp., Japan's largest phone company, and TransTeleCom ZAO of Russia will start operating a fiber-optic link between the two countries from as early as next month, an NTT official said Tuesday.

The cable's cost is put at "dozens of millions of dollars," and will be operational from April or May, Takashi Ooi, vice president of network integration at NTT Communications Corp., a unit of NTT, said in an interview in Hong Kong.

The undersea link extends 570 km, connecting Hokkaido and Russia's Sakhalin, Tokyo-based NTT said in February 2007.

NTT aims to bolster revenue from its fiber-optic network to reduce reliance on its mobile phone business.