FBI director James Comey is to testify Monday at a public hearing of the Intelligence Committee in the House of Representatives on Russia-linked meddling in the 2016 US elections.
A statement from the committee said that the open hearing was called as part of its "investigation into Russian active measures during the 2016 election campaign."
Comey is also expected to discuss President Donald Trump's claims, which he has failed to back up with any evidence, to have been wiretapped by the government under his predecessor, Barack Obama.
US intelligence agencies last year declared that hacking against Democratic Party organizations, which led to leaks of embarrassing information about the left-leaning party and its presidential nominee, Hillary Clinton, was very likely directed by the highest levels of the Russian government.
Mike Rogers, director of the National Security Agency, which is responsible for overseas electronic surveillance, is on Monday's witness list from the Intelligence Committee.
Last week, Comey briefed the Senate Intelligence Committee in private about Russian election meddling, amid questions about possible ties between the Trump campaign and the Kremlin.
Congressman Devin Nunes, a California Republican and chairman of the committee, said Sunday that Obama did not "go and physically wiretap something. So if you take the president [Trump] literally, it didn't happen."
"Was there a physical wiretap of Trump Tower? No," Nunes told US broadcaster Fox News.
Trump, who first tweeted the wiretapping claim on March 4, last week predicted that "some very interesting items" would be revealed regarding his allegations.