Botox-maker Allergan is nearing a deal to be purchased by Actavis that could produce one of the world's top pharmaceutical companies, The Wall Street Journal reported Sunday.

Long sought by Canadian rival Valeant, Allergan appears to have reached an outline of an agreement with Actavis, the Journal reported.

The agreement, also confirmed by the Financial Times, is due to be formalized Monday before the opening of the New York Stock Exchange.

According to the Times, Actavis is offering to buy Allergan at $215 a share, which would value the company at $64 billion. The purchase would be in shares and cash.

The proposal would dwarf the $53 billion that Valeant has put on the table for months. In late October, the Canadian group said it was considering increasing its proposal to $60 billion.

If the sale to Actavis goes through, Allergan would rebuke its largest shareholder, activist investor Bill Ackman.

With a 9.7 percent stake in Allergan, Ackman supported Valeant in November and called for the Botox company to open negotiations with the two prospective buyers.

Allergan refused to engage in discussions with Valeant. Acquiring US firm Allergan was seen as critical to Valeant's strategy for development and cost reductions.

If Actavis acquires Allergan, it would create a company significantly diversified in brand-name and generic drugs, particularly in dermatology, gynecology and ophthalmology.

The expanded company could generate about $23 billion in sales per year, making it one of the world's largest pharmaceutical firms.