Marguerite Reardon/CNET

Lawmakers on Capitol Hill are planning a broad antitrust investigation of Silicon Valley tech giants, which have been under intense scrutiny over their scale and power.

The probe was announced Monday by Rep. David N. Cicilline, a Democrat from Rhode Island and chairman of the House Antitrust Subcommittee. The investigation, which will look into tech juggernauts including Facebook and Google, is meant to explore whether big tech companies are engaging in "anti-competitive conduct." It will also try to decide if the government's current antitrust laws and enforcement policies are enough to fix the problems.

"The growth of monopoly power across our economy is one of the most pressing economic and political challenges we face today. Market power in digital markets presents a whole new set of dangers," Cicilline said in a statement. "After four decades of weak antitrust enforcement and judicial hostility to antitrust cases, it is critical that Congress step in to determine whether existing laws are adequate to tackle abusive conduct by platform gatekeepers or whether we need new legislation to respond to this challenge."

The probe will include a series of hearings held by the Subcommittee on Antitrust, Commercial and Administrative Law, Cicilline's office said.

Representatives from Facebook and Apple didn't immediately respond to requests for comment. Google, Amazon and Twitter declined to comment.

The announcement of the investigation comes as Silicon Valley giants face severe criticism that their market dominance could be stifling competition and hurting consumers. Sen. Elizabeth Warren, a Democratic 2020 presidential candidate, has made it a key part of her platform to break up the big tech companies, including Google, Facebook and Amazon. Last month, Chris Hughes, a Facebook co-founder, also called for the breakup of the company he helped create.

Meanwhile, the Department of Justice and Federal Trade Commission, the two US agencies that handle antitrust issues, have also shown renewed interest in investigating Silicon Valley. The agencies reportedly decided which tech companies they'd be responsible for probing. The Justice Department will take Google and Apple, while the FTC takes Facebook and Amazon, according to The Wall Street Journal.

Regulators in Europe have been more aggressive when it comes to antitrust issues with big tech companies. In March, Google was hit with a $1.7 billion fine from the European Commission for "abusive" online ad practices. The commission said the search giant exploited its dominance by restricting its rivals from placing their search ads on third-party websites. And last year, the EU's executive arm fined Google a record $5 billion for unfair business practices around Android, its mobile operating system.