WASHINGTON- President Donald Trump is questioning what he says is a "fake" dossier of allegations about his connections to Russia.

Here's his latest tweet: "Workers of firm involved with the discredited and Fake Dossier take the 5th. Who paid for it, Russia, the FBI or the Dems (or all)?"

The political research firm behind the dossier balked this week at subpoenas from the House Intelligence Committee. A lawyer for the firm questioned the legitimacy of the committee's investigation into Russian meddling in the 2016 election.

The dossier contends the Russian government amassed compromising information about Trump and was engaged in an effort to support and assist him.

The Associated Press has reported that special counsel Robert Mueller's investigators have spoken with the former British spy who helped compile the dossier.