WASHINGTON (Reuters) - Two U.S. senators on Friday unveiled bipartisan legislation to toughen penalties on robocalls, make it easier for regulators to crack down on unwanted calls and compel mobile phone providers to adopt call authentication technologies.

FILE PHOTO - A businessman sits on a bench looking over his mobile phone in downtown San Francisco, California February 4, 2016. REUTERS/Mike Blake

Senator John Thune, a Republican who chairs the Commerce Committee, and Senator Ed Markey, a Democrat, introduced legislation that would also bring federal agencies and state attorneys general together to “address impediments to criminal prosecution of robocallers.” The bill is also backed by the incoming chair of the committee, Republican Senator Roger Wicker.

The bill would broaden the authority of the Federal Communications Commission to impose penalties of up to $10,000 per call that intentionally flout telemarketing restrictions.

YouMail, a company that blocks robocalls and tracks them, estimated there were 5.1 billion unwanted U.S. calls last month, up from 3.4 billon in April.

U.S. regulators have taken a number of actions to try to deter robocalls or automated, prerecorded calls that regulators have labeled a “scourge.”

“Existing civil penalty rules were designed to impose penalties on lawful telemarketers who make mistakes. This enforcement regime is totally inadequate for scam artists and we need to do more to separate enforcement of carelessness and other mistakes from more sinister actors,” Thune said.

The bill would require carriers to adopt technology to verify that incoming calls are legitimate before they reach consumers’ phones and require new rules to help protect subscribers from receiving unwanted calls or texts from callers using unauthenticated numbers.

The bill also would extend the statute of limitations to three years up from one year for the FCC to impose robocall fines and direct federal agencies and state attorneys general to work together on prosecuting robocallers.

Three consumer groups praised the bill on Friday. Consumer Reports said “spoofed robocalls have become a major intrusion into consumers’ everyday lives, and an all-too-convenient vehicle for scammers.”

FCC Chairman Ajit Pai on Friday said on Twitter he is pleased that the bill “would make it easier for the @FCC to go after illegal #robocall scams by extending the statute of limitations for enforcement actions.”

Pai earlier this month wrote the chief executives of major telephone service providers and other companies, demanding they launch a system no later than 2019 to combat billions of robocalls and other nuisance calls received monthly by American consumers.

The letters went to 13 companies including AT&T Inc, Verizon Communications Inc, T-Mobile US Inc, Alphabet Inc, Comcast Corp, Cox Communications Inc [COXC.UL] and Sprint Corp.

Federal Trade Commission Chairman Joe Simons said this week that two-thirds of consumer complaints made to the agency are about unwanted calls. The FTC has begun publishing caller ID numbers of robocallers in consumer complaints so apps and telecommunications companies can use the data to block unwanted calls. Simons also urged Congress to give the FTC jurisdiction to investigate telecommunications companies as warranted.