Democrats on the House Judiciary Committee have asked the FBI to investigate Attorney General Jeff Sessions.
Mr Sessions has been under fire since it emerged he met Russian ambassador Sergei Kislyak during Donald Trump’s presidential campaign.
A policy adviser to the Republican candidate as Mr Trump fought for the presidency, he did not disclose the communications when he was asked at his confirmation hearing whether “anyone affiliated” with the campaign had contact with Moscow.
“We would ask the FBI and the United States Attorney’s Office for Washington, D.C., to take up an immediate criminal
investigation into these statements, which could potentially implicate a number of criminal laws including Lying to Congress and Perjury,” a letter sent to FBI Director James Comey and US Attorney Channing Phillips read.