FALLS CHURCH, Va. – General Dynamics on Monday extended its tender offer for all outstanding shares of common stock of Newport News Shipbuilding Inc. to midnight Sept. 21.

The earlier deadline was midnight Sept. 14, and the Falls Church-based defense contractor said about 16 million shares had been tendered by then, compared to 22.6 million shares tendered before an earlier deadline of Aug. 31.

The lower number of shares was attributed to last week’s closing of U.S. financial markets and other disruptions caused by the Sept. 11 terrorist attacks in New York and Washington, D.C.

General Dynamics is awaiting government approval to complete the acquisition.

The proposed $2.1 billion cash merger, announced in April, has drawn scrutiny from the Defense and Justice departments, which have antitrust concerns. The deal would make General Dynamics the sole manufacturer of Navy aircraft carriers and submarines. Two years ago the Pentagon scuttled a merger between the two companies.

Los Angeles-based Northrop Grumman, General Dynamics’ primary competitor for Navy shipbuilding contracts, also has offered $2.1 billion for the Newport News yard. Executives at the Newport News-based builder of nuclear-powered aircraft carriers and submarines have said they prefer General Dynamics’ all-cash offer.