Larry Page, Google co-founder and CEO speaks during the opening keynote at the Google I/O developers conference.

Some of the biggest names in technology have been lavishing millions on Congress during the third quarter, according to government documents — at a time when they're under increasing regulatory scrutiny from Washington.

The disclosures, required by the Lobbying Disclosure Act, revealed Google spent $4.17 million lobbying Congress this most recent quarter. Facebook spent $2.85 million, while Twitter spent $120,000. The figures were first reported by Bloomberg News.

Last quarter Google spent $5.93 million lobbying lawmakers, while Facebook and Twitter spent $2.38 million and $120,000 respectively.

The three tech titans are sending lawyers to U.S. congressional committees on Nov. 1 to testify on their behalf in response to Russian political ad buying on their platforms during the 2016 election.