Reuters reported on Wednesday that Pfizer's talks to acquire Allergan had accelerated, as the U.S. Treasury prepares to clamp down further on tax inversions.

Pfizer will offer more than 11 shares for each Allergan share held, CNBC said on Thursday

The offer would value Allergan at at least $366.41 (239.68 pounds) per share, or a total of more than $144 billion.

The deal would result Pfizer to domicile in Ireland.

The Treasury this week will clamp down further on tax-avoiding "inversion" deals done by U.S. companies with foreign rivals, according to a letter obtained by Reuters on Wednesday.

Pfizer shares were down 1.6 percent in early trading, while Allergan's were down 1.8 percent.

(Reporting by Ankur Banerjee in Bengaluru; Editing by Savio D'Souza)

Stocks treated in this article : Allergan, Inc., Allergan plc, Pfizer Inc.