The office building of health insurer Anthem is seen in Los Angeles, California February 5, 2015. REUTERS/Gus Ruelas/File Photo

(Reuters) - A federal judge is expected to block a proposed deal between health insurer Anthem Inc ANTM.N and Cigna Corp CI.N as soon as Thursday, the New York Post reported, citing sources.

Anthem, which operates Blue Cross Blue Shield health insurance plans in 14 U.S. states, is trying to buy smaller rival Cigna. The government sued seven months ago to stop the deal, saying it was anti-competitive.

Judge Amy Berman Jackson of the U.S. District Court for the District of Columbia has not yet issued an opinion on the case. The trial began late last year, and Cigna said it ended on Jan. 4.

Anthem is preparing for an appeal of any ruling that doesn't go its way and insiders expect Jackson to rule against the deal, the Post reported. (nyp.st/2iWTcUq)

Anthem said earlier on Thursday it extended the deadline for its acquisition of Cigna by three months.

Anthem and Cigna could not be immediately reached for comment.