(Adds details from decision, background, case citation)

April 12 (Reuters) - A federal appeals court on Tuesday revived a long-running class-action lawsuit accusing Pfizer Inc of misleading shareholders about the safety of its Celebrex and Bextra pain-relieving drugs.

The 2nd U.S. Circuit Court of Appeals in Manhattan said a lower court judge erred in excluding testimony by Daniel Fischel, a former University of Chicago Law School dean hired as an expert by the shareholders to assess potential damages.

It also said the judge erred in finding that no reasonable jury could find Pfizer liable for statements made by G. D. Searle & Co and Pharmacia Corp, which previously made Celebrex and Bextra.

Pfizer did not immediately respond to requests for comment. A lawyer for the plaintiffs had no immediate comment.

Concerns about the safety of Celebrex and Bextra mounted after the release of medical studies in late 2004, when rival Merck & Co withdrew its own Vioxx drug because of associated cardiovascular risks.

Shareholders of Pfizer accused the New York-based company of having concealed tests that began in 1998 regarding the safety of Celebrex and Bextra, and which indicated similar risks.

Pfizer pulled Bextra from the U.S. market in April 2005. It agreed in September 2009 to pay $2.3 billion to settle a U.S. Department of Justice probe into the marketing of drugs including Bextra.

The lawsuit covered investors who bought Pfizer stock between Oct. 31, 2000 and Oct. 19, 2005, a period in which the company's market value slid by more than $100 billion.

Tuesday's decision returns the shareholder lawsuit to U.S. District Judge Laura Taylor Swain in Manhattan. Swain had dismissed the case in July 2004.

The case is In re: Pfizer Inc Securities Litigation, 2nd U.S. Circuit Court of Appeals, No. 14-2853.

(Reporting by Jonathan Stempel in New York; Editing by Chizu Nomiyama and Jonathan Oatis)