BRUSSELS — European officials said on Friday that Google had submitted proposals aimed at ending a three-year antitrust case focused on its search service, but the offer did not prevent rivals from seeking to prolong its legal entanglements.

Neither the company nor European officials were willing on Friday to describe the settlement proposals. But Google has been expected to offer revisions to the way it conducts its search business in Europe to address regulators’ concerns that its activities were unfair to other Web publishers and its online competitors.

The two parties are still negotiating the terms of the proposed settlement, and a final agreement is expected in the coming week, according to a person briefed on the negotiations who spoke on condition of anonymity while the agreement was still under discussion.

Google’s competitors did not take a wait-and-see attitude. After filing a new complaint against Google on Thursday, Icomp, an industry group backed by Microsoft, urged European regulators on Friday to approach the company’s proposal with caution.