Alphabet Inc's Google disclosed on Tuesday that it spent a company-record $21.2 million on lobbying the United States government in 2018, topping its previous high of $18.22 million in 2012, as the search engine operator fights wide-ranging scrutiny into its practices.

Google declined to comment beyond its filing.

Facebook Inc disclosed that it also spent its most ever on US government lobbying in 2018, $12.62 million. That was up from $11.51 million a year ago, according to the Center for Responsive Politics data.

Microsoft Corp spent $9.52 million on lobbying in 2018, according to its disclosure on Tuesday, up from $8.5 million in 2017.

Lawmakers and regulators have weighed new privacy and antitrust rules to rein in the power of large internet service providers such as Google, Facebook Inc and Amazon.com Inc .

Google Chief Executive Sundar Pichai, who testified in December before a US House of Representatives panel for the first time, has said the company backs the idea of national privacy legislation. But he has contested accusations of the company having a political bias in its search results and of stifling competition.

The company disclosed that among new lobbying areas in the fourth quarter were its search technology, criminal justice reform and international tax reform. Google is perennially among the top lobbying spenders in Washington.

Regulatory backlash in the United States, as well as Europe and Asia, is near the top of the list of concerns for Alphabet investors, according to financial analysts. Shares of Alphabet closed down 2.6 percent on Tuesday.

The company appointed former General Electric executive Karan Bhatia as its head of global policy last year. Susan Molinari, Google's top U.S. public policy official, stepped down to take on an advisory role this month.

Amazon.com Inc's filing was expected later on Tuesday.