(Reuters) - Botox maker Allergan Inc (>> Allergan, Inc.), which is fending off an acquisition by Valeant Pharmaceuticals Inc (>> Valeant Pharmaceuticals Intl Inc), said on Monday it had been approached by another party regarding a potential transaction.

The company is Actavis Plc (>> Actavis PLC), a source familiar with the situation said.

Allergan, which made the disclosure in a regulatory filing on Monday, had said it was looking for acquisitions but has not previously said it had been contacted about a deal.

Valeant and Pershing Square Capital Management, which owns nearly a 10 percent stake in Allergan, made an offer now worth $55 billion (34.41 billion pounds) for Allergan at the end of April.

Allergan has been fighting the takeover and is trying to convince investors that Valeant's plan for cost-cutting is too extreme.

Reuters reported in early October that Actavis, which had already reached out to Allergan once in the prior months, was planning a second approach to the company with an offer worth more than $200 per share.

Last week during a conference call with analysts, Allergan Chief Executive Officer David Pyott was asked if the company had received an offer from another party besides Valeant. He responded that he could not comment on "any particular market rumor."

Valeant, whose cash and stock offer is worth about $182 per share, recently said it was prepared to raise its offer so that it would be worth around $200 per share.

Activist investor William Ackman, who runs Pershing Square, spearheaded calling a special meeting of Allergan shareholders to vote on new board members. Allergan set the date for Dec. 18.

Allergan, which has sued Valeant and Ackman for insider trading, is waiting to decide on the Actavis approach to see if a California judge will issue a temporary injunction to exclude Ackman from voting at the meeting, a second source familiar with the situation said.

If the ruling goes against Allergan, that could push Allergan to the table with Actavis, he said. A hearing on the issue was held last Tuesday and a ruling is expected any day.

Separately, Allergan confirmed that business development head David Lawrence had left the company recently. His departure followed that of Allergan's top financial executive, who left this summer for family reasons.

"David Lawrence made the decision to retire from Allergan in the beginning of September to commit more time to his health and family," an Allergan spokesman said in a statement.

The spokesman declined to comment on e-mails written by Lawrence and disclosed as part of an insider trading lawsuit in which he described being "paddled" by the company's top executive for suggesting to tone down a presentation called "Valeant is Vile."

Allergan shares rose $2.83, or 1.5 percent, to $192.89, about 6 percent above Valeant's offer price, while Actavis gained $5.22, or 2 percent, to $247.70. Valeant gained 0.3 percent to $133.37 in New York Stock Exchange trading.

(Reporting by Caroline Humer and Nadia Damouni; Editing by Dan Grebler)

By Caroline Humer and Nadia Damouni