UPDATE 3-Gabelli backs Harbinger's Media General slate

(Adds more ownership details)

NEW YORK, April 16 (Reuters) - Harbinger Capital Partners won support on Wednesday from shareholder Mario Gabelli in its boardroom battle with Media General Inc (MEG.N), but a proxy advisory firm advised siding with the newspaper company.

Fund manager Gabelli, whose funds hold more than 22 percent of Media General, said he would tilt his vote toward Harbinger's proposed slate of three directors in a letter to the company's chief executive filed on Wednesday with U.S. securities regulators.

Shares in the company closed up 2 percent at $14.34 on the New York Stock Exchange. Gabelli's Gamco Asset Management owns 14.9 percent of Media General shares and Gabelli Funds holds almost 7.5 percent, according to a filing.

But later in the day, advisory firm Proxy Governance urged Media General shareholders to vote for the directors proposed by the company's management rather than siding with Harbinger.

"While we believe the dissident critique has certain merits, we have significant questions whether the dissident slate ... would have sufficient time or experience to effect change," Proxy Governance said in a statement.

Another proxy advisory firm, Glass Lewis & Co, said this week it supported one Harbinger board nominee, while RiskMetrics recommended that shareholders vote for two of the rival nominees.

Harbinger, which owns 18.2 percent of Media General, said in a statement it was "gratified" that Gabelli agreed with its push for significant change at the company.

As well as publishing newspapers such as the Tampa Tribune, Media General also owns television stations, some of which it bought from NBC, owned by General Electric (GE.N).

In his letter dated April 15, Gabelli cited Harbinger's significant Media General stake as well as the company's decision to buy NBC stations despite his opposition as grounds for supporting the Harbinger slate.

Gabelli also said that if Media General enlarges its board, Gamco would ask for the opportunity to suggest candidates that share capital allocation.

On April 1, Media General Chief Executive Marshall Morton dismissed Gabelli's proposed strategy for the company. He has also urged shareholders to reject the three board nominees proposed by Harbinger.

Harbinger has argued that Media General should cut publishing costs more aggressively and consider lowering its dividend and using the money to pay down more debt. (Reporting by Sinead Carew and Robert MacMillan; Editing by Dave Zimmerman, Braden Reddall and Gunna Dickson) (email: sinead.carew@reuters.com; +1 646-223-6186))