WASHINGTON (Reuters) – Representatives of Facebook, Twitter and Google have been asked to appear on Nov. 1 at hearings on alleged Russian interference in U.S. politics called by the U.S. Senate and House Intelligence Committees, officials said.

Facebook and Twitter have already agreed to send representatives to the Senate committee hearing, a Congressional official said.

An official knowledgeable about House committee plans declined to disclosed whether the companies have agreed to send representatives to its hearing.

Sources said that Google had not yet notified the committees that it would send representatives to the hearings, though ultimately the company was likely to do so.