BRUSSELS, July 16 (Reuters) - U.S. grains merchant Bunge has offered to sell Glencore-backed Viterra's crush and refining plants for oilseeds in Hungary and Poland in order to secure EU antitrust approval for the $34 billion merger, a person close to the deal said on Tuesday.

The companies, which announced the deal a year ago to better compete with global giants Archer-Daniels-Midland and Cargill, submitted concessions to the EU competition enforcer last week.

They offered to divest assets in two EU countries, other sources told Reuters last week.

Viterra has 13 oilseed crushing plants among its more than 30 processing and refining facilities in 11 countries, according to its website.

The European Commission, which is scheduled to decide on the deal by Aug. 1, has sought feedback from farmers' groups, clients and rivals before deciding whether to accept Bunge's offer.

"We are confident that the commitments we have offered address the areas of concern expressed by the Commission, which are limited to specific markets," Bunge said. (Reporting by Foo Yun Chee, Editing by Louise Heavens)