William Ackman's Pershing Square has been pushing for a special meeting of Allergan shareholders to consider the removal of six directors and the appointment of its slate of nominees.

"We believe Pershing Square's attempt to replace a majority of the Allergan Board is a further effort to support Valeant in its bid to acquire Allergan at a grossly inadequate price," Allergan said on Friday.

The company has been trying to fight off a $53 billion hostile offer from Valeant Pharmaceuticals International Inc and activist investor William Ackman since late April.

Allergan is expected to unveil details of its plan to remain a stand-alone company when it releases second-quarter results this month.

The company has said it is considering acquisitions of its own, additional spending cuts or taking on debt to buy back shares.

(Reporting By Anjali Rao Koppala; Editing by Joyjeet Das)