Oracle is braced for a formal objection from Brussels to its planned $7.4bn (£4.5bn) acquisition of fellow US technology company Sun Microsystems, escalating the company's legal wrangle with Europe's competition authorities.

The US software company has refused to offer any concessions to European regulators to meet their concerns about the deal, according to one person close to the process. That has left Brussels close to issuing an official statement of objections, the first step on the path to blocking it, this person added.