Companies with misleading claims on the impact of the Gillard government's planned carbon tax will face heavy penalties, Treasurer Wayne Swan said today.

Mr Swan, who is also Deputy Prime Minister says the Australian Competition and Consumer Commission (ACCC) "will keep a watchful eye out for any shonky attempts to jack up prices and falsely claim it is related to the carbon price."

Australia’s competition regulator will employ at least 20 new staff to monitor and investigate any false or misleading claims about the impacts of new levy.

The Gillard government has provided ACCC with $12.8 million funds to carry out the new role over four years.

Under the newly introduced Australian Consumer Law, the commission will have the power to prosecute companies to investigate claims of price gouging, with penalties of up to $1.1 million for each breach of the law.

Due to operate from July 1 next year, the carbon price will have only a modest impact on most prices, according to Mr Swan.

Treasury modelling estimates it will only add 0.7 per cent to the inflation rate in 2012-13.

"That is why we have put in place assistance for households ... to ensure they can meet those price impacts," Mr Swan said.