* Fourth-quarter earnings $1.05/share vs est $1.03
* Fourth-quarter sales $1.06 bln vs est $1.05 bln
* Sees full-year earnings $4.45-$4.65/share vs est $4.64
By Siddharth Cavale and Arpita Mukherjee
Feb 19 (Reuters) - Herbalife Ltd, the diet supplements company that has become a battleground for Wall Street titans William Ackman and Carl Icahn, raised its 2013 earnings forecast on Tuesday.
The company also revealed in a regulatory filing the staff of the Security and Exchange Commission's Division of Enforcement has been inquiring about the company's operations since December.
The company, which sells products through a network of independent distributors, has come under intense scrutiny from Pershing Capital Management's Ackman, one of the world's most closely watched hedge fund managers, who in December revealed a short position in the stock and called the business "a pyramid scheme."
Herbalife said it contacted the regulator following Ackman's allegations and that it would fully cooperate with the inquiries.
Ackman had argued that the company is an unsustainable scheme because distributors earn more than 10 times as much from recruitment as they do by selling its products.
The company has refuted the allegations and said a majority of its distributors join Herbalife just to get a discount on the products rather than to earn money.
Shares of the company, which tumbled dramatically after Ackman's allegations, have more than recovered their losses. The stock also got a boost after Icahn and another hedge fund manager, Daniel Loeb, revealed long positions in the company.
Icahn revealed a 13 percent ownership stake last week, while Loeb took an 8.2 percent stake in the company earlier this year.
Herbalife shares were down marginally in trading after the bell on Tuesday after closing at $39.74 on the New York Stock Exchange.
The company raised its earnings outlook to $4.45 to $4.65 per share for the full year, from $4.40 to $4.55 per share. Wall Street analysts were expecting $4.64 per share.
The forecast, however, excludes $10 million to $20 million in legal and other costs to respond to Ackman's attacks on the company as well as the impact of the devaluation of the Venezuelan bolivar.
The company's fourth-quarter income rose to $117.8 million, or $1.05 per share, from $105.4 million, or 86 cents per share, a year earlier.
Revenue rose about 20 percent to $1.06 billion, slightly above Wall Street's expectations of $1.03 billion.
Sales in Asia Pacific, which is the largest revenue generator for Herbalife, rose 19 percent to $295.2 million in the quarter.