Black & Decker Manufacturing Co. is being investigated by the Justice Department on monopolization charges concerning the Baltimore firm's tool accessories section, a company official said yesterday.

Eugene Allen, a Black & Decker vice president, acknowledged the investigation, which came to light in court papers filed in an attempt to quash an Antitrust Division demand for documents and interrogatories.

In a telephone interview, Allen said the company "has no practices which have as their intent the monopoly of the accessories market."

The papers, filed in federal court in Baltimore, point out that the company's share of the accessories market is 5 percent and that complying with the government's request will cost Black & Decker more than $875,000 and would take up more than 51,000 working-hours, Allen said.

Allen said the "broad request" calls for the production of documents relating to any transaction involving the distribution of the accessories, which include parts such as power tool bits.

The company, which Allen said reported world-wide sales of about $1.2 billion, has asked the court to throw out the Justice Department request. A Justice Department official said the request for documents is "appropriate," and said the department would challenge the Black & Decker motion.

The investigation centers on monopolization, or attempted monopoly statues, covered by the Sherman Act, Allen said.

Although Allen acknowledged that Black & Decker would like to increase its share of the $700 million accessories market, he said the company's share of the business, in terms of its own sales figures, has been decreasing. "We don't feel there is justification for this," he said.

The company, under the government's request, would have had to submit the materials today, had it not filed the motion in court. The government has to respond by the end of next week, Allen said.