The US House Intelligence Committee has asked the Executive Branch for any evidence that would support President Donald Trump's claim that his phones were tapped at Trump Tower during last year's election.
A senior congressional aide said the committee has asked that the information be provided by Monday.
The aide said the request came in a letter sent by the committee chairman, Devin Nunes of California, and the panel's ranking Democrat, Adam Schiff of California. Other politicians have made similar requests.
Mr Trump has said his predecessor Barack Obama had the phones tapped.
He has not provided evidence to support his claim and has asked Congress to investigate.