WASHINGTON- U.S. lawmakers, including some Democrats, will receive classified briefings from FBI and intelligence officials on Thursday on an FBI probe into Russian election meddling after President Donald Trump made unsubstantiated claims about an informant being used against him.

Two Republican lawmakers, and no Democrats, were expected to attend the first meeting to review classified information relating to a recent suggestion by Trump that the FBI might have used an informant to gather information on his 2016 election campaign. 

A second briefing was scheduled for Republican and Democratic leaders from the Senate and House of Representatives, known as the Gang of Eight, according to a Justice Department spokeswoman.

White House spokesman Raj Shah said earlier on Wednesday that second briefing would take place some time after the Memorial Day holiday on Monday.

Senate Democratic leader Chuck Schumer had said on Wednesday that Democrats should be included as a "check on the disturbing tendency of the president’s allies to distort facts and undermine the investigation and the people conducting it.”

Schumer welcomed the decision to brief the Gang of Eight promptly but questioned why there should be a separate briefing for the two Republicans, U.S. Representatives Devin Nunes and Trey Gowdy, chairmen of the intelligence and oversight committees.

"What is the point of the separate briefing if not to cause partisan trouble” Schumer said in a statement on Thursday.

FBI Director Christopher Wray, Director of National Intelligence Dan Coats and Deputy Attorney General Rod Rosenstein were scheduled to attend both meetings, along with White House Chief of Staff John Kelly, according to the Justice Department.

The FBI was investigating whether anyone in Trump's campaign had worked with Moscow to influence the election outcome in Trump's favor. Federal Special Counsel Robert Mueller took over that probe in May 2017 after Trump fired FBI Director James Comey.

The New York Times reported that the person working for the FBI was used to get information from people in Trump's campaign about Russian hacking of Democratic emails, not to spy on Trump.

Trump's closest conservative allies in Congress have been clamoring for access to the classified documents. The lawmakers have accused the FBI and Justice Department of political bias against Trump in favor of his Democratic rival, Hillary Clinton, during his successful presidential campaign.

(Reporting by Sarah N. Lynch and Doina Chiacu; Editing by Bernadette Baum) ((doina.chiacu@thomsonreuters.com; 202-898-8322;))