VicHealth has says there needs to be a crack down on social media influencers advertising alcoholic brands without revealing they are being paid to do so.

It's time to call last drinks on 'influencers' using social media to sell cocktails, wine and champagne, VicHealth says.

Victoria's health promotion foundation looked into Australia's top 70 Instagram influencers and found almost three quarters featured alcoholic drinks in their posts, but only a quarter fully revealed they'd been paid to do so.

VicHealth Acting CEO Dr Lyn Roberts said the "underhanded" nature of the social media posts made it difficult for young people to know when they were being sold an ad.

"We also know that young people who like or follow alcohol brands on social media are twice as likely to drink at risky levels than those who don't," Dr Roberts said.

"For every advertising dollar spent, young people drink three per cent more alcohol."

The research found big alcohol companies were using social media as a key tool to promote their products as cool and glamorous to an impressionable audience.

And while there are no rules that stipulate influencers must disclose sponsorship deals, VicHealth says it's time for that to change.

VicHealth on Monday launched a Top Spin, a statewide competition encouraging young people to call out sneaky tactics used by the alcohol industry to influence them to drink.

Key findings of the research:

• A total of 73 per cent of top influencers featured alcoholic drinks in their Instagram accounts in the past year. But only 26 per cent featured a fully disclosed sponsored alcohol collaboration with a brand.

• Of the likely sponsored mentions (12 per cent), 61 per cent were disclosed and 39 per cent were undisclosed, meaning they did not feature a hashtag such as #sponsored #ad or #collab nor used the 'Paid partnership' option for brands on Instagram.

• Influencer attendance at events sponsored by alcohol brands and posts containing branded glasses/cups further blur lines of what's considered sponsored versus non-sponsored.

• Little consistency in disclosing paid collaborations. The 'paid partnership' Instagram feature was rarely used for alcohol collaborations. A number of different hashtags are used, for example: #collab, #ad, #spon, #partner, #sponsored.

• Some influencers don't disclose a paid collaboration but use the official campaign hashtags, which denote a paid partnership. Some posts had hallmarks of a collaboration with no clear disclosure.

• Alcohol brands prefer to partner with mega (100,000+ followers) and macro (10,000-100,000 followers) influencers to deliver an average of three posts for a sponsored campaign, usually in the form of the influencer posed with a bottle of the alcohol.

• Cocktails, wine and champagne are by far the most popular types of alcohol featured.

Source: VicHealth