In an open letter addressed to Facebook, dated 1 May, DCMS committee chair Damian Collins said that answers provided by the company’s chief technology officer Mike Schroepfer, who appeared before the committee, were not substantial enough.

“The Committee feels that the evidence lacked many of the important details that we need,” wrote Collins in the letter. He re-stated the government’s earlier invitation to Zuckerberg to appear in London in person to provide oral evidence.

If Zuckerberg fails to do so, the committee threatened to issue a formal summons for him to appear the next time he is in the UK.

“There are over 40 million Facebook users in the UK and they deserve to hear accurate answers from the company he [Zuckerberg] created and whether it is able to keep their data safe,” wrote Collins.

Zuckerberg appeared in front of US Congress in April and is reported to be giving evidence to the European Parliament later this month.

Collins asked Facebook to provide clarity on the 39 questions Schroepfer failed to answer fully by 11 May, and also asked for confirmation of Zuckerberg’s attendance by the same date. He has been asked to appear before MPs before 24 May.

The points for clarification, also listed in the letter, include a question on the number of Facebook and Instagram users in the UK who were contacted by non-UK entities during the EU referendum, and a query on how Facebook defines political adverts.