BRUSSELS/MADRID (Reuters) - French telecoms group Orange (>> ORANGE SA) is set to secure European Union approval for its 3.4-billion-euro ($3.79 billion) deal to acquire Spanish fixed line network operator Jazztel after offering to strengthen rivals in Spain, four people familiar with the matter said on Thursday.

Orange, which hopes the deal will help it better compete with Vodafone (>> Vodafone Group plc) in the Spanish market after Vodafone acquired cable operator Ono last year, submitted concessions to the European Commission last month. It has since modified them slightly.

"The merger will be approved," said one of the sources, who declined to be named because the European Commission has yet to announce its decision. The other sources also said the deal was going to be approved.

They said Orange had offered to sell overlapping assets with Jazztel, including parts of Jazztel's fibre optic network, and to wholesale ADSL (broadband) capacity to rivals.

Jazztel currently sells mobile services as a mobile virtual network operator using the Orange network.

A Commission spokeswoman and Orange declined to comment. The Commission has set a June 1 deadline for its decision.

European Competition Commissioner Margrethe Vestager is scheduled to speak at an event in Madrid on May 20.

(Additional reporting by Leila Abboud in Paris; Editing by Greg Mahlich)

By Foo Yun Chee and Andres Gonzalez

Stocks treated in this article : ORANGE SA, Jazztel PLC, Vodafone Group plc