UPDATE 5-Areva to sell division, hike capital to fund growth

* Areva board agrees to increase capital by 15 pct

* Areva says board agrees to sell T&D unit

* Capital to be opened to industrial and strategic partners

* Areva to sell stakes in Eramet and STMicroelectronics

* Needs 11 bln eur for investments, buyback of Siemens stake

(Recasts with CEO conference call)

By Marie Maitre and Benjamin Mallet

PARIS, June 30 (Reuters) - Areva's (CEPFi.PA) supervisory board approved plans to increase the nuclear reactor supplier's capital and sell one of its key businesses to bridge a $15.5 billion funding gap, the state-controlled group said.

Areva needs the funds to stay at the forefront of the nuclear industry as countries including Britain and the United States look to expand their atomic programmes to ensure the security of energy supply as fossil fuels become more scarce.

Under the terms of a long-awaited plan to finance its development needs around the world, Areva said on Tuesday that it would also sell minority stakes it holds in mining group Eramet (ERMT.PA) and chip maker STMicroelectronics (STM.PA)

"The Areva supervisory board has decided to open up its capital to strategic and industrial partners, to the value of 15 percent, mainly by increasing its capital," Areva said, confirming information obtained by Reuters from union sources.

Areva Chief Executive Anne Lauvergeon, who had lobbied the French government for a rights issue, declined to say who these new partners might be.

"Strategic partners by definition are not clients, that is power groups, and not suppliers," she only said when asked in an analyst conference call whether Bouygues (BOUY.PA), a 30-percent shareholder of Alstom could take a stake in the company.

Sources familiar with the matter have told Reuters that Areva's capital could be opened to Mitsubishi Heavy Industries (MHI) (7011.T) and Middle Eastern sovereign funds.

MHI said on Friday it would consider buying a stake in Areva if it received such an offer from the French government.

The rights issue will also be opened to holders of investment certificates, which trade on the Paris stock market and represent 4 percent of Areva's capital, the group said.