UPDATE: THE ACCC has warned shopkeepers not to blame taxes for a sharp increase in cigarette prices.

The Federal Government has increased the tax on cigarettes by between 11c and 28c a packet as part of the half-year increase in excise.

The slug in the so-called "sin taxes'' for smokers and drinkers will also mean the tax on a bottle of spirits reaches $20.

The changes are part of the automatic rise in indexation introduced 30 years ago by Bob Hawke and are expected to pour millions of dollars extra into the fragile federal Budget.

From today, retailers, shopkeepers and bar staff must collect the extra tax.

Other factors such as competition, business costs and profit margins could mean prices paid by consumers may be more or less than the tax rise and vary between brands.

Smokers will be slugged 11c more for a pack of 20 cigarettes, 14 cents extra for a pack of 25s and will pay 16 cents more tax for a pack of 30s. The tax on a packet of 40s increases by 22 cents while the excise on a pack of 50s climbs by 28 cents to $17.72.

A smoker buying a pack of 30s every day will pay $74 tax for their weekly habit.

But smokers contacted the Herald Sun to report that prices had risen by as much as $2.40 a pack.

The ACCC confirmed it had received complaints. It said businesses were free to set their own prices, but they must not blame the excise changes.

It said business must be able to prove any claims it makes about price changes.

Assistant Treasurer David Bradbury's office said if a consumer thinks a business is falsely linking a price rise with excise change they should report it to the ACCC hotline 1300 305 502.

Beer drinkers will pay 24c more tax on a slab of 24 full-strength 375ml cans with Canberra's take now $15.21 of the price they pay.

The tax on a slab of light beer rises 9c to $5.40.

A 285ml pot served over the bar will rise by 1c if it is full strength but will be unchanged if it is light.

Spirit drinkers will hand over an extra 54c in tax for a slab of 24 cans of pre-mixed spirits, taking the taxman's share to $34.37.

A six-pack of pre-mixed spirits will attract 13c more excise, while the tax on a 700ml bottle of spirits jumps by 32c to $20.05 a bottle.

The tax office said the excise rates were based on the rise in the Consumer Price Index over the past six months.

Wine taxes are not affected.

The Howard government's freeze to petrol taxes in 2001 means motorists are paying about 15c-a-litre less tax at the fuel pump.