The UK competition regulator initiated a probe into a planned acquisition of graphic interchange format (GIF) picture provider Giphy by Facebook, a move which put the reportedly multi-million dollar deal on hold indefinitely.

In a statement, the Competition and Markets Authority (CMA) said the investigation would explore whether the acquisition might result in “a substantial lessening of competition in any market or markets in the UK”.

The CMA said it sent an enforcement order to Facebook and Giphy, adding acquisition activities can’t be made while the probe is taking place.

Comments regarding the investigation are invited until 3 July, with further actions to then be confirmed by the watchdog.

Facebook unveiled its move for Giphy last month: it plans to integrate the company’s services into its Instagram subsidiary. At the time, the social media giant noted 50 per cent of Giphy’s traffic came from its services.

Axios reported the price tag was $400 million, though the stakeholders did not confirm any numbers.

US senators have also expressed concerns around the competitive impact of the acquisition, The Verge noted.