A research and development company has accused...

A research and development company has accused Irvine Sensors Corp. of Costa Mesa of fraud and breach of contract in a $20.4-million lawsuit over an agreement to provide the technology for an infrared detection device for tactical military use.

Irvine Sensors denied Friday that it improperly charged cost overruns or released confidential information to unauthorized parties in violation of its $4-million contract with PruTech Research & Development Partnership of San Jose.

James Alexiou, Sensors president, said the company would “vigorously” defend the suit. He said that a PruTech principal, Irv Weiman, was a director of Sensors until Wednesday, the day before the suit was filed, and never voiced the complaints listed in the suit at the company’s board meeting Dec. 13.