Law enforcement officials are seeing increased efforts by scammers looking to take advantage of the novel coronavirus pandemic to prey on U.S. consumers, according to the FBI and other agencies.

The Federal Communications Commission in the past week has sought to raise awareness by releasing several examples of spam calls that have circulated since the virus spread in the U.S.

"If you want to receive a free testing kit delivered overnight to your home, press 1," a voice on one of the calls says. "Protect your loved ones from the coronavirus."

Tune into ABC at 1 p.m. ET and ABC News Live at 4 p.m. ET every weekday for special coverage of the novel coronavirus with the full ABC News team, including the latest news, context and analysis.

Another example showed a suspected scammer trying to advertise a cleaning service that purported to eliminate the virus from the air in Americans' homes.

"For only $79 our highly trained technicians will do a full air duct cleaning and sanitation to make sure that the air you breathe is free of bacteria," a voice on the call said.

In one case out of North Carolina, a robocall falsely warned residents that they might be infected by the virus.

"People are getting calls at home and being told by the local health department that they have come into contact with someone who has the coronavirus," North Carolina Attorney General Josh Stein warned in a news conference last week.

Federal and state officials have been raising alarms for weeks now about such suspected instances of fraud, have threatened legal action and -- in at least one instance -- opened a criminal investigation of people they say are looking to profit off deceiving the American public about the coronavirus.

Following action from the Justice Department over the weekend, a federal court ordered the shutdown of a website, "CornavirusMedicalKit.com" that offered visitors a vaccine kit for the coronavirus for a shipping charge of only $4.95.

"In fact, there are currently no legitimate COVID-19 vaccines and the WHO (World Health Organization) is not distributing any such vaccine," the Justice Department said in a statement announcing the enforcement action.

The DOJ did not disclose the owners of the website, who prosecutors are now investigating over promoting a false vaccine.

FBI Director Chris Wray in a video message to the bureau's workforce last week warned agents to be vigilant about investigating such crimes in the weeks and months ahead.

"The last thing the American people need, in the middle of this pandemic, is criminals trying to take advantage of them and profit off their concerns," Wray said.

The FBI and FCC in warnings to consumers have offered the following urgent tips for consumers:

Be wary of any business, charity, or individual requesting payments in cash, by wire transfer, gift card or through the mail.

Never share your personal or financial information over email, text message or over the phone.

Know that government agencies will never call you to ask for money.

The Justice Department has separately urged Americans to report suspected fraud schemes related to COVID-19 by calling the National Center for Disaster Fraud (NCDF) hotline at 1-866-720-5721 or by emailing the NCDF at disaster@leo.gov.

What to know about coronavirus:

How it started and how to protect yourself: coronavirus explained

What to do if you have symptoms: coronavirus symptoms

Tracking the spread in the US and Worldwide: coronavirus map