Japan's NTT DoCoMo has decided to form a capital alliance with Indian telecommunications company Tata Teleservices, it confirmed Wednesday.

The two companies will detail their plans at a news conference in Tokyo at 7pm local time (10am GMT). At the news conference Ryuji Yamda, president of NTT DoCoMo, and Anil Sardana, senior vice president of Tata Teleservices, will speak.

Earlier in the day, Japan's Sankei newspaper reported that DoCoMo plans to buy a 25 percent stake in the Indian cellular carrier. A later report in The Nikkei newspaper said DoCoMo will pay about ¥260 billion (US$2.7 billion) for a 26 percent stake.

NTT DoCoMo is Japan's largest cellular carrier and its 54 million subscribers give it a 51 percent share of the market. Two weeks ago it outlined a strategic growth plan that calls for an expansion of its revenue from international businesses and investments and alliances with carriers mainly in the Asia-Pacific region.

Tata Teleservices is a mobile telecom service provider in India. It has recently launched the Blackberry device in India after a long discussion with the government over security concerns because Blackberry messages are more difficult to intercept than those on conventional cellular messaging systems.