Social-networking website Facebook has held meetings with private equity firms to explore raising another round of funding, the New York Post reported on Thursday, citing sources.

Facebook could not be immediately reached for comment.

Facebook held valuation discussions with Providence Equity Partners, General Atlantic, Bain Capital, Kohlberg Kravis Roberts, among others, the paper said, citing multiple sources close to or involved in the situation.

The process has been informal and no term sheets have been drawn up, the sources told the paper.

The private-equity firms value the website in the $2 billion to $3 billion range, lower than Facebook's estimate of $5 billion to $6 billion, the sources told the paper.

The talks have created friction with Facebook's existing investors, who have poured in $400 million into the website and would like a return on their investment before seeing their stakes diluted through a new round of funding, the paper said.

Facebook's existing investors include Greylock Partners, Meritech Capital Partners and Microsoft Corp .

(Reporting by Ajay Kamalakaran in Bangalore; editing by Simon Jessop)

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