The European Union is reportedly set to grant unconditional approval to Facebook’s $19bn acquisition of mobile messaging startup WhatsApp.

Reuters quoted a person familiar with the matter as saying: "It’s unconditional clearance."

The decision is scheduled to be announced on October 3. The deal, which is the largest in Facebook’s 10-year history, is expected to expand the company’s presence in the rapidly-growing mobile messaging market.

Facebook’s WhatsApp deal was approved by the US regulators in April, notifying WhatsApp to follow its existing privacy practices upon the merger.

However, in May, Facebook sought the European Commission to probe its WhatsApp takeover in order to avoid multiple investigations from several European nations.

The social network’s move came in the midst of escalating pressure from European telecom firms, which fear market dominance by Facebook.

With plans to add free voice-call services for its 450 million customers by late 2014, WhatsApp has now turned out to be a potential rival to Deutsche Telecom and Telefonica.

The transaction involves $4bn in cash and $12bn worth of Facebook shares, along with $3bn in restricted stock to WhatsApp’s founders and employees.

The value of the transaction is more than what Facebook raised when it went public.