The U.S. attorney's office here and a federal grand jury in New York are investigating one of the nation's largest electronic surveillance firms in connection with multimillion dollar traffic in everything from bomb detectors to bugging devices.

The New York-based firm, CCS Inc., whose major client was Iran before that country's recent revolution, was raided by local police earlier this month who seized about $100,000 in equipment that police said was illegal.

The raid was the third on the firm in less than 18 months.

CCS is also under investigation by a separate federal grand jury in New York for its alleged involvement in shipping electronic surveillance equipment overseas.

The firm also is being probed by the New York State Select Committee on Crime for its ties to the February Winter Olympic games at Lake Placid, N.Y. CCS has advertised itself widely as "electronics security supplier" for Lake Placid, but Olympic officials have disputed CCS's role.

A New York official said 40 infrared sniperscopes were among equipment in CCS crates seized by customs agents at Kennedy Airport last March.

State officials have expressed concern that security at the Winter Games could be breached by terrorist groups who might have gained access to CCS's extensive stock of bomb detection, eavesdropping and monitoring devices.

Federal officials in New York said "it would be premature to say" the New York and Washington probes are coordinated but acknowledged that police are exchanging information.

Undercover D.C. police raided CCS's Georgetown office on Dec. 9 after the firm held a $350 per person electronics security seminar Dec. 6-7 at the Watergate Hotel. An undercover officer, posing as a private investigator, attended the seminar and later was shown a variety of equipment, including a microphone hidden in a watch, according to court records.

Police arrest Edward Williams Jr., 55, of Vienna, Va. and charged him with possessing illegal devices designed primarily to intercept private conversations surreptitiously. Williams was also a CCS agent in July 1978 when local police confiscated equipment from the firm, which was then located at 3507 R. St. NW. No arrests were made at that time.

Following the July raid, customs asgents a month later seized the company's local records and shifted the investigation of New York.

U.S. attorneys delayed action against the company here while the investigation was continuing in New York, a Justice Department official said. The U.S. attorney's office here recently resumed investigating the 1978 case.

CCS attorney Barry Slotnick said the firm "welcomes the investigations. Maybe once and for all we can finish up with this nonsense."

The New York state investigation involves CCS's business contacts with overseas clients and the business activities of CCS president Ben Jamil, state crime committee officials said.

CCS spokesman Gerald Freeman, who said his firm's major clients include such Middle Eastern governments as Saudi Arabia and Kuwait, said CCS is spending more than $350,000 to supply equipment for the games next February. Olympic officials in Lake Placid deny this, saying the firm has only offered to supply -- but has not delivered -- a few bullet-proof vests and metal detectors similar to airport security devices.