Two influential Republican senators issued a criminal referral this week against Christopher Steele, the former British spy who authored the largely unverified "Trump dossier."

Sen. Chuck Grassley, R-Iowa, and Sen. Lindsey Graham, R-S.C., referred Steele to the Department of Justice for allegedly making false statements to investigators. It was not immediately clear from the referral what Steele allegedly lied to investigators about.

The referral was made Thursday but revealed Friday. Democrats on the committee said they were not consulted.

Grassley is the chairman of the Senate Judiciary Committee, which has been conducting an investigation running parallel to special counsel Robert Mueller's probe into Trump's alleged ties to Russia.

"I don't take lightly making a referral for criminal investigation. But, as I would with any credible evidence of a crime unearthed in the course of our investigations, I feel obliged to pass that information along to the Justice Department for appropriate review," Grassley said in a statement.