A federal appeals court denied on Thursday Microsoft Corp's request that a full panel of judges rehear arguments in its long-running patent dispute with a small Canadian technology company.

The decision is a blow to the world's largest software maker, which has been embroiled in a dispute with Toronto-based i4i Ltd over a feature in Microsoft's Word application for more than three years.

Microsoft could yet take the case to the U.S. Supreme Court, or make a new request to the appeals court. The company is considering its options, according to a spokesman.

A federal jury awarded i4i $290 million last August after finding that Microsoft had infringed a patent belonging to i4i relating to text manipulation software in the 2003 and 2007 versions of Word, Microsoft's word processing application.