* Plans to invest are at an early stage - sources

* Nokia Siemens Networks recently bought Motorola unit

(Adds background, Bain Capital)

By Megan Davies

NEW YORK (Reuters) - Blackstone, TPG
Capital and Bain Capital are among private equity
firms eyeing a stake in wireless network equipment maker Nokia
Siemens Networks, sources familiar with the situation said.

Plans to invest in the firm, owned by Nokia and
Siemens, are at an early stage, the sources said.

The Wall Street Journal, which first reported that several
private equity firms were interested in Nokia Siemens Networks,
said a stake in the firm would cost at least $1 billion.

Represenatives of Nokia and Nokia Siemens declined to
comment, while efforts to contact a Siemens representative were
unsuccessful.

Earlier this month, Nokia Siemens Networks struck a deal to
buy Motorola's telecom network equipment business for
$1.2 billion in an effort to penetrate the U.S. market, where
it has struggled.

The U.S. market generates only 6 percent of its revenue.

Nokia Siemens Networks also recently won an eight-year
contract worth more than $7 billion with an upstart U.S.
operator called LightSquared, which is looking to build a
high-speed wireless network to offer wholesale services in the
fiercely competitive market.

Motorola and Nokia Siemens Networks have had a hard time
battling bigger players to win business with large telephone
companies in the cutthroat mobile gear market.

(Reporting by Megan Davies; additional reporting by Sinead
Carew in New York and Jessica Hall in Philadelphia; Editing
Gary Hill and Ted Kerr)