The US Office of Special Counsel has opened an investigation into allegations that the Trump campaign's use of the White House as an Election Day command center violated federal law, Democratic Representative Bill Pascrell said on Thursday. 

In a statement, Pascrell said the federal watchdog responded on Thursday to his call for a probe, telling him a special unit "has opened an investigation into these allegations to determine if the Hatch Act was violated."

President Donald Trump monitored election returns in the living room of the White House residence on Tuesday, later addressing some 200 supporters gathered in the East Room. Pascrell had asked the special counsel, Henry Kerner, to investigate reports suggesting that Trump used space in the adjacent Eisenhower Executive Office Building - on the grounds of the White House - as a campaign "war room."

The New Jersey lawmaker said Trump was also expected to be briefed in the White House residence and the Oval Office throughout the day by campaign officials, which he said put executive branch officials at risk of violating federal law.

The White House denied any violation of the federal law.