Facebook is investing record amounts to try to influence the US government as scrutiny over its role in last year’s election leads to calls for tougher regulations on the company on Capitol Hill.

Hours before Sheryl Sandberg, its chief operating officer, arrived in Washington for meetings with members of Congress and journalists last night, the company said that it spent more than $5.6 million on lobbyists in the first half of the year.

Mark Zuckerberg, Facebook’s billionaire chief executive, has taken to calling members of Congress directly, the Bloomberg news website said.

The increased spending comes as Silicon Valley’s “Big Tech” companies come under mounting pressure to explain their role in the most unpredictable presidential election in modern history. In recent weeks light has been