Twitter Inc. (TWTR) - Get Report slumped in pre-market trading Monday after media reports linked the social media group to Cambridge Analytica, the British political consultancy at the heart of Action Alerts PLUS holding Facebook Inc.'s (FB) - Get Report data scandal.

Weekend reports from the U.K.'s Telegraph newspaper alleged that Twitter sold some of its data to Aleksandr Kogan, the Cambridge University researcher whose app was allegedly used to harvest information from Facebook users that then found its way to Cambridge Analytica, which used the information to influence the 2016 Presidential elections. A second report from the Sunday Times, in conjunction with Swansea University, suggested as many at 6,500 Twitter accounts that sent messages in support of Jeremy Corbyn, the Labour Party leader who challenged U.K. Prime Minister Theresa in last year's elections, were so-called "bots" that could be traced to Russian servers.

"These new revelations are extremely concerning," said U.K. Secretary of State for Digital, Culture, Media and Sport Matt Hancock of the Russian bot allegations. "It is absolutely unacceptable for any nation to attempt to interfere in the democratic elections of another country."

Twitter shares were marked 2.28% lower in pre-market trading in New York Monday, indicating an opening bell price of $28.34 each, a move that would trim the stock's year-to-date gain to 18%. 

The reports could reignite concern that the social media group's international growth, which help lift first quarter ad sales by a forecast beating 21% in the first three months of this year, may be at risk if regulators in either the United Kingdom or the European Union propose harsher crackdowns on the collection of users' information and its subsequent sharing with advertizers looking to target specific customers.

"We're always going to do the right thing to make sure that the service is great for those that should be on it, and that's going to be removing spam and suspicious accounts whenever we can, and we continue to improve at that," CFO Ned Segal told investors on a conference call earlier this month. "UThe EU's General Data Protection Regulation) could have some impact over time. And then we may make decisions over time that affect MAU, and we just want to flag it."