Private equity firm Elevation Partners has invested USD 120 million in Facebook Inc by buying shares of the social networking site, a media report said.

Attributing to people familiar to the situation, The Wall Street Journal stated, "Elevation Partners has acquired an additional five million shares in Facebook Inc for USD 120 million."

Earlier, the PE firm had bought 2.5 million shares of Facebook for USD 90 million in November last year, the report added.

The WSJ quoted a spokesperson of the social networking site: "Facebook is a private company, and we don't typically disclose financials or comment on our valuation. We're focused on building our business to be successful over the long term."

The report cited a person familiar to the development as saying that Elevation decided to invest again in Facebook due to the strong growth registered by it.

The number of Facebook users have grown to about 500 million from 325 million when the PE firm had first invested in it.

Other investors in Facebook include venture capitalists and Microsoft Corp, which invested USD 240 million for a 1.6 per cent stake plus some exclusive ad rights.