RUSSIAN mafia attacks on online betting networks in Alice Springs crashed Telstra's local network, leaving the city of 23,000 people without email for more than five hours and taking the nation into "uncharted territory" of net blackmail.

The nation's biggest telco admitted yesterday that the attack took it offline, sparking claims from the betting industry that Telstra was not doing enough to secure its network.

The Australian revealed on Friday that the sophisticated blackmailers cost two online bookies -- Multibet.com and Centrebet -- millions of dollars by shutting down their networks after the bookmakers refused to buckle to demands of $US20,000 ($28,584) and $US10,000 respectively.

The revelation that the May attack knocked out Telstra's entire internet platform came as another online betting site -- Davidson Sportsbetting

.com.au -- revealed it had also been the target of Russian crime gang extortion attempts at the same time as Centrebet and Multibet.

Hamish Davidson, the owner of Wollongong-based Sportsbetting, said he had received a series of ransom demands via email. When he refused to pay, the gang attacked the website.

"We were down the first time for three to four days," said Mr Davidson. "But I was not going to pay."

Australian Federal Police, Interpol, the FBI, and Britain's National High-Tech Crime Centre have been investigating the Russian and Eastern European crime gangs targeting online bookies, and the AFP has been briefing the industry about the growing scourge.

Telstra spokesman Rod Bruem said the attack on Multibet.com and Centrebet in late May brought their "system to a standstill".

Mr Bruem said that there were "new and vicious" things coming all the time, and in some cases they were in "uncharted territory".

Mike Miller from Multibet, one of the original blackmail targets, said Telstra had not taken the situation seriously enough.