CANBERRA-Australians have been warned to be wary of a new scam that has seen bank accounts drained by stealing mobile phone numbers.

The Telecommunications Industry Ombudsman (TIO) issued the warning on Wednesday, confirming that the government is working with top telecommunications providers to improve security.

The scam involves a fraudster stealing a target's mobile phone number by asking their telco to switch the number to a new SIM card in the perpetrator's possession.

Scammers then use the mobile phone number to access their target's bank accounts, emails and other online accounts, stealing thousands of dollars.

TIO Judi Jones said that authorities were fighting an uphill battle to stay ahead of scammers who are using increasingly complex schemes.

"The Telecommunications Industry Ombudsman's Systemic Investigation Team noticed a trend of complaints in 2018 about mobile service providers who had a low bar for consumer identity verification," she told News Corp Australia on Wednesday.

"We have been working with these providers to address these problems and help prevent future complaints," she said. "We welcome the industry's continued work towards consistently robust identity verification procedures," she said.

"It is important to ensure these procedures keep up with evolving technological risks," she added.

Jones called on the industry to introduce more robust security checks such as requiring a second form of identification before a phone number can be moved to a new SIM. 

According to Scamwatch, the government's official tool for reporting scams, Australians lost 900,000 Australian dollars (645,091 U.S. dollars) to tax-related scams alone in the three months between November 2018 and the end of January 2019.