BRUSSELS (Reuters) - U.S. drugmaker Pfizer (>> Pfizer Inc.) has offered concessions in a bid to win European Union regulatory approval for its $15 billion takeover of U.S. rival Hospira (>> Hospira, Inc.), the European Commission said on Tuesday.

The EU competition authority did not provide details of Pfizer's proposal in line with its policy. It extended the deadline for its decision to Aug. 4 from July 20 to examine the concessions.

It can either clear the deal if it considers Pfizer has allayed competition concerns regarding the deal or open a full-scale investigation.

Pfizer, maker of impotence treatment Viagra and cholesterol drug Lipitor, is making its biggest ever acquisition aimed at expanding its portfolio of generic injectable drugs and copies of biotech medicines.

Hospira makes generic versions of injectable drugs used in hospitals, pumps to deliver such medicine and also sells biosimilars or copies of biotech drugs.

(Reporting by Foo Yun Chee; Editing by Mark Potter)

Stocks treated in this article : Pfizer Inc., Hospira, Inc.