Facebook will reportedly win unconditional EU approval for its $19 billion offer for mobile messaging startup WhatsApp ,Reuters reported on Thursday. Facebook convinced the Commission that the deal had no anti-competitive effect and, therefore, concessions were not necessary, Reuters' sources said.

The acquisition would be the largest in Facebook's 10-year history and would give the company a firm foothold in the mobile messaging market.

WhatsApp plans to offer free voice-call services for its millions of customers later this year, makeing it a potentially powerful competitor to companies telecom companies.

The European Union competition authority has set an Oct. 3 deadline for its decision.

U.S. regulators gave the green light for the deal in April, telling WhatsApp to stick to its current privacy practices after the merger, including not to use users' personal data for targeted ads.