Facebook and Twitter have agreed to hand over to British authorities information related to the social media reach of Russian-backed posts during the Brexit referendum in 2016, The Guardian reported on Tuesday.

Damian Collins, the chairperson of the British Parliament’s digital, culture, media and sport committee, said the information could give the United Kingdom a better idea of whether Russia tried to influence the referendum.

Facebook and Twitter wrote to Collins this week saying that his committee and the UK’s Electoral Commission had asked them for information about Russian interference into Britain’s referendum to leave the European Union. Facebook will submit the information by early December, while Twitter said it “intends to share our findings in the coming weeks”.

Collins told BBC’s Radio 4 Today programme that he was concerned by the “systematic distribution of false news by particularly Russian-backed organisations”, The Guardian reported. He said the United States and Britain knew about one fake news agency operating out of Saint Petersburg in Russia, but there would “probably be others and we may find other countries doing it too”.

Researchers at the University of Edinburgh had earlier in November identified 419 accounts operating from the Russian Internet Research Agency, attempting to influence UK politics.

In October, Facebook had said that an estimated 10 million people in the United States saw political, divisive advertisements on the social media platform before and after its 2016 presidential elections. It submitted more than 3,000 such advertisements paid for by the Russian Internet Research Agency to US Congressmen investigating Moscow’s meddling in the elections.