The pair have responded to demands from the head of the digital, culture, media and sports (DCMS) committee Damian Collins to provide information about Russian-linked adverts on their sites during the EU referendum last year.
And both firms have also revealed they have been contacted by the Electoral Commission, which is also investigating Brexit campaigning. They said they would respond to both requests in the coming weeks and before the end of the year.
Collins asked for information in the wake of investigations by lawmakers in the US, where intelligence agencies have identified Russian influencers the US Presidential elections last year, as part of a DCMS inquiry into fake news.
Several academic research papers in recent weeks have identified accounts linked to Russia that were active during the referendum. And the Prime Minister Theresa May has even gone as far as accusing her counterpart in Russia, Vladimir Putin, of "sowing discord in the West".