A spokesman for The Office of Liquor Gaming and Racing has confirmed it is investigating a second advertising campaign by CrownBet for its "Norm Smith Medal" betting, which has been pushed in an on-air and online campaign.

"There are also a number of other investigations under way involving other licensed wagering operators who are also publishing gambling-related inducements but it would not be appropriate to discuss further details on these matters as it could prejudice current inquiries," the spokesman said.

He said OLGR will continue to monitor gambling-related advertisements across all mediums and will take appropriate regulatory action if they are found to breach NSW's Racing Administration Regulation 2012, which prohibits publishing advertising that offers NSW residents any credit, voucher or reward as an inducement to participate in gambling or open an betting account. The maximum fine for companies is $5500.

A spokesman for CrownBet declined to comment.

Sports betting agencies have noticeably stepped up their battle for market share this year. The Standard Media Index showing that, in the year to August, $149.1 million was spent on gambling ads, up from $104.5 million for the same period last year.

The frenzy of new ads has been followed by complaints.

International player William Hill has boasted in an advertisement that its live betting "is so easy that a competitor even made a complaint".

It is understood that the complaint was aimed at an advertisement in which William Hill was making a parody of competitor Tabcorp's ad campaign. A complaint was made to the Australian Communications and Media Authority.

William Hill has been under investigation over its live betting, known as In-Play, which allows betting after the start of play and can be accessed online or by using a phone app.

Its CEO, Tom Waterhouse, announced on Friday they will be including a new In-Play betting system for horse racing which will allow betting for the first 20 seconds of any race.

Tabcorp also allows bets on live sport through TAB outlets and through telephone-operator betting. But a spokesman said: "We don't offer it online or through mobile apps as Australian law doesn't permit it."

A spokesman for the Minister for Racing, Deputy Premier Troy Grant, said: "The government is monitoring the changing gambling sector and will continue to evaluate its policies to ensure they, and the associated penalties, reflect the contemporary gambling environment."

Greens MP John Kaye said: "CrownBet has graphically demonstrated that the laws against using rewards to encourage more online wagering are seen as entirely optional by the industry.

"Despite exposure in the media last weekend, the promotional offer has continued for another seven days," said Dr Kaye.

"Even if it were imposed, a fine of just $5500 would be seen as a minor cost of doing business in an industry which turns over millions of dollars a day.

"Unless serious penalties are imposed that would see business damaged or shut down, vulnerable demographics will continue to be targeted for recruitment into problem gambling," Dr Kaye said.