Trying to head off a European investigation of its business practices, Microsoft Corp. said yesterday it would release an unprecedented amount of information about how its core products interact with other software developers' programs.

Analysts said Microsoft hoped the publication of tens of thousands of pages of technical documentation, previously kept secret to all but those who licensed it, would blunt criticism that the software giant uses its monopoly power to hamstring competition.

European Union officials weren't persuaded, noting in a written response that Microsoft had made previous pronouncements about plans to help rival programs work with its Windows operating system, Office productivity suite and server software for running networks of machines.