Facebook said it may extend the deadline for closing the $19 billion deal to acquire the world’s most popular messaging service provider, WhatsApp.

In its recent quarterly report filed with the US Securities and Exchange Commission, Facebook said it agreed to a termination fee of $1 billion in cash and an issue of common stock shares of the equivalent value if the deal was not closed by 19 August 2014.

The company said it may extend the closing date to 19 August 2015 if the closing conditions applicable to Facebook, other than certain regulatory approvals, have been satisfied.

It added that it expects this to be the case and that the deal should close during the second half of 2014.

The company clearly has confidence that the transaction will go through, but that regulatory approval may not come before the original deadline for the deal to close.

Rivals of WhatsApp were reportedly approached by European Union antitrust officials earlier this month regarding the proposed acquisition.

Sources told The Wall Street Journal that detailed questionnaires were sent to a number of technology and messaging companies, with the aim of gauging how the deal could potentially affect competition in the market.

The move comes ahead of a formal review of the deal by the European Commission, which is unlikely to have taken place had Facebook not requested it, as WhatsApp does not generate enough revenue in Europe to trigger an investigation automatically.

The social networking giant asked the EC to conduct a review covering all 28 countries within the EU in May to avoid the possibility of separate reviews in multiple markets.

The US Federal Trade Commission notified Facebook and WhatsApp about their obligations to protect consumer privacy in April, including the fact that post-merger WhatsApp must continue to honour prior promises made to consumers.