LOS ANGELES, JUNE 15 -- U.S. Customs Service agents posing as brokers for South African businessmen arrested a Los Angeles engineer and charged him with illegally attempting to sell them technical data from a restricted Strategic Defense Initiative (SDI) missile research project, federal authorities said today.

Prosecutors said the engineer, Ronald J. Hoffman, 51, was also under investigation for exporting or agreeing to export similar data to at least four Japanese industrial firms over the past four years.

Federal authorities said they were uncertain whether any of the Japanese firms were aware that the technology was being sold illegally.

Assistant U.S. Attorney William F. Fahey said that documents, computer records and facsimile machine files seized Thursday night during a search of Hoffman's home indicated that the engineer's alleged SDI sales to the Japanese may have netted him "hundreds of thousands of dollars."

In a 52-page affidavit filed in U.S. District Court in Los Angeles, authorities said that they were also investigating allegations that Hoffman, working through his defense contracting firm, Plume Technology, illegally exported or agreed to sell missile software systems to firms in West Germany and Italy and also to Israel's Ministry of Defense.

Fahey said that Hoffman had boasted of being in contact with the head of the Israeli government's missile program.

Hoffman was arrested Thursday at a hotel moments after he accepted a $150,000 check from a Customs agent.