Warner Communications Inc. said its Atari Inc. unit had sued Coleco Industries Inc., charging patent infringement and unfair competition and seeking damages of more than $350 million.

It also seeks an injunction against the manufacture and sale of Coleco's Expansion Module No.1, which, Atari contends, is intended to allow its VCF compatable cartridges to be played on Colecovision's home video game unit.

Coleco responded by fililng a $500 million counterclaim, charging violations of antitrust law. Coleco said it does not infringe any valid patent and that the Atari suit is without merit.