UPDATE 1-Tech executives to testify at U.S. Congress' Russia hearings

(Updates with Senate hearing, background)

WASHINGTON, Sept 27 (Reuters) - Executives from Facebook , Alphabet Inc's Google and Twitter will appear in the U.S. Congress in the coming weeks as lawmakers probe Russia's alleged interference in the 2016 U.S. election, committee sources said on Wednesday.

A Senate aide said executives from the three firms had been asked by the Senate Intelligence Committee to testify at a public hearing on Nov. 1.

The leaders of the House of Representatives Intelligence Committee said the panel would hold an open hearing with technology companies as part of its investigation.

"In the coming month, we will hold an open hearing with representatives from tech companies in order to better understand how Russia used online tools and platforms to sow discord in and influence our election," the committee's top Democrat, Representative Adam Schiff, and Representative Mike Conaway, the Republican leading the investigation, said in a statement.

They did not immediately identify any companies. But a committee source said the House panel hoped to hear from the same firms.

"We anticipate it will be necessary for the American people to hear directly from tech companies like Facebook, Twitter and Google, as well as other relevant experts," the source said.

Some U.S. lawmakers, increasingly alarmed about evidence that hackers used the internet to spread fake news and otherwise influence the 2016 election, have been pushing for more information about the influence of social networks in particular.

The Senate and House intelligence committees are two of the main congressional panels probing allegations that Russia sought to interfere in the U.S. election to boost Republican President Donald Trump's chances at winning the White House, and possible collusion between Trump associates and Russia.

Moscow denies any such activity, and Trump dismissed any talk of such collusion.

(Reporting by Patricia Zengerle and Dustin Volz; Editing by Peter Cooney)