Fines for throwing away items such as lolly wrappers or chip packets have increased to $150 under the new regime, which also includes a fresh approach to managing extreme cases of hoarding.

The changes, which represent the most significant overhaul of the ACT's littering laws in 15 years, are designed to combat what the government believes is an increasing problem in the territory.

City Services Minister Chris Steel said the government spent more than $3 million cleaning up litter in the past financial year, including $550,000 alone on illegally dumped items - a 30 per cent increase from 2017-18.

"Littering and illegal dumping is a problem that occurs in many forms across all areas of our city," Mr Steel said.

"From the dropping of food wrappers to the dumping of trailer loads of rubbish ... these actions have important impacts on the well-being of our people and the environment and they do not have a place in our community."

The ACT Greens and Canberra Liberals supported the legislation, but not before raising concerns about the government's approach.

Dropping a syringe or lit or unlit cigarette in public will attract fines of $500 under the new offence of aggravated littering.

The penalties are intended to reflect the health and safety risks associated with leaving a syringe in a public place, and the potential for a cigarette butt to spark a fire.

Greens crossbencher Caroline Le Couteur was concerned that the "clearly well-intended" legislation would disproportionately affect rough sleepers, as well as drug and alcohol users.

"Let's be clear - the Greens don't condone littering," she said.

"[But] slapping huge littering fines on the homeless, or on drug and alcohol users, isn't rehabilitative - it's punitive. It isn't going to change behaviour. It will not make our community safer."

Ms Le Couteur questioned if the fines were even necessary, given that the government has issued just eight warnings, and laid no charges, for litter offences in the past three years.

Opposition urban services spokeswoman Nicole Lawder also highlighted the apparent lack of enforcement, querying the purpose of tough penalties if they aren't policed.

But Ms Lawder was supportive of efforts to clean up the city, saying feedback from residents indicated that "standards have fallen" across Canberra.

Under the new laws - which will come into effect in the coming weeks - the size of the fines and penalties imposed will be linked to the amount of litter dumped.

Dumping one to 10 litres of litter would attract a $500 fine. That would increase to $1000 for dumping between 10 and 200 litres, and $1500 for leaving between 200 to 1000 litres.

The new laws will also give the government more power to quickly remove abandoned vehicles. Once a car is "reasonably suspected to be abandoned", it can be treated as litter, giving officers the green light to enter the vehicle.

A new framework for handling cases of extreme cases of hoarding will also be introduced, following the passage of the new laws.

Fines or penalties would not be imposed for hoarding offences to ensure that "mental issues are not criminalised". Government officers will only enter a site to clean up the property once all other options have been exhausted.

"Hoarding can have serious safety risks to both to the occupants of the property with the hoarding issue and surrounding land," Mr Steel said.

"However we also know that cases of extreme hoarding on private land are complex and sensitive, and often involve underlying mental health issues."