The Securities and Exchange Commission accused United Technologies Corp. yesterday of violating the securities laws in its 1978 bid to take over Carrier Corp.

In a civil suit filed in U.S. District Court here, the commission charged UTC with attempting to acquire secretly Carrier shares it had failed to get in a legitimate tender offer.

The SEC says that UTC, a Hartford firm, announced on Dec. 7, 1978, that nearly 20 million shares of Carrier common and a class of preferred stock had been tendered, and that it would acquire 85.07 percent of the tendered stock, or about 17 million shares, in accordance with the announced terms of the tender offer.

But three weeks later, UTC discovered that only about 19 million shares of Carrier had been tendered. If UTC had acquired 85.07 percent of the lesser amount, ti would not hold a majority of Carrier's outstanding stock. As a result, UTC would not be free to put its own representatives on the Rochester company's board of directors.

The SEC said UTC did not disclose its miscalculation on the number of shares tendered. Instead, according to the suit, UTC:

Purchased, or attempted to purchase, 100 percent of the tendered shares rather than 85.07 percent.

Bought shares tendered after expiration of the offer.

United Technologies Holding Corp., UTC's parent, also is named as a defendant.

The Justice Department has also filed suit to block the UTC-Carrier merger on antitrust grounds.

UTC issued a statement yesterday saying that it had acted "lawfully and in good faith" in the Carrier acquisition and that "the SEC complaint is totally unwarranted."