BRUSSELS, Belgium (AP) _ The European Economic Community is considering creating a European company to promote recently developed technology for a cinema-quality television system, a senior source said Monday.

The source, who asked not to be named, said the executive commission of the EEC was expected to adopt a proposal this week to create a ''European company for research and promotion'' of high-definition television (HDTV).

It would encourage production of shows in HDTV, establish studios with HDTV technology and organize HDTV demonstrations. Companies of EEC countries involved in developing HDTV could join the European venture.

HDTV produces sharper, brighter images on a wider TV screen with high- quality sound.

Demand for HDTV, which promises to bring cinema-quality pictures to TV screens, is expected to surge in the next few years. Industry insiders see a world market for HDTV sets of around $100 billion by 1991.

EEC companies are working on a European HDTV system in competition with Japan, where NHK, the state-owned broadcaster, is poised to launch HDTV after a series of demonstrations of the technology earlier this year.

The United States is also developing an HDTV standard that will be incompatible with the Japanese standard and may be incompatible with the European standard as well.

The EEC firms - Robert Bosch GMBH of West Germany, Philips International BV of the Netherlands, Thomson SA of France and Britain's Thorn EMI PLC - might want to join the new European company, the source said.