BRUSSELS (Reuters) -European Union antitrust regulators will seek feedback next week on Google's proposals to comply with tech rules aimed at promoting fair competition, people with direct knowledge of the matter said on Wednesday, which could decide whether it faces formal charges.

The European Commission launched an investigation in March into Google to see if it favours its vertical search engines such as Google Shopping, Google Flights and Google Hotels over rivals, and whether it discriminates against third-party services on Google search results.

The move came after rivals, which include comparison shopping sites, said Alphabet's Google had not complied fully with the EU's Digital Markets Act (DMA) aimed at reining in the power of Big Tech and to create a level playing field for smaller competitors.

Google's latest proposals aim to create a separate box for rivals below its own product listing ads box in Google search results to address criticism from comparison shopping sites, the people said.

The company also offered to create two different boxes next to each other, with one showing intermediaries and the other for direct suppliers such as airlines, hotels and retailers, they said.

The Commission will hold workshops separately for these groups from Sept. 9 to 11 to get their views on the proposals, the people said. Google has not been invited to the events.

"The workshops in September are about Alphabet's compliance with Article 6.5 DMA on self-preferencing and involve a variety of third parties," the EU competition watchdog said in an email.

Google said: "We have engaged with the European Commission and industry stakeholders over the past year, receiving and responding to feedback in an effort to balance a wide spectrum of views across the ecosystem. We will continue to engage over the coming months."

Failure to allay the regulatory concerns could result in formal charges against Google by the end of September that could lead to a hefty fine as much as 10% of its global annual turnover, the people said.

(Reporting by Foo Yun Chee; Editing by Emelia Sithole-Matarise)