A Federal Government MP says he supports decriminalising marijuana and wants some taxes and restrictions on tobacco removed because double standards on the issue gives him the "irrits".

George Christensen, who is an outspoken Queensland Liberal National MP and the Member for Dawson, shared an image on his Facebook page which claimed smoking marijuana caused more damage to lungs than smoking tobacco – it was being used to attack anti-smoking campaigners.

The post generated a robust discussion about the effects of marijuana and tobacco, which prompted Mr Christensen to criticise both the criminalisation of marijuana and taxes on tobacco.

"Not that I agree that this is a reason to ban pot," he wrote.

"But what gives me the irrits is the double standards over restricting smoking versus a relaxed attitude to pot.

"My preference would be both to be legal with a lot of the taxes and restrictions removed."

Tobacco tax increases will raise $5.3 billion over four years

Mr Christensen has taken a free-market approach to car subsidies and corporate welfare in recent weeks, calling on car companies to pay back their taxpayer subsidies and backing the Government's hardline stance on industry assistance.

The Coalition Government agreed with the former Labor Government's four-stage tobacco excise increases which began last December; they will raise $5.3 billion over four years.

It also did not oppose Labor's plain packaging legislation, which was rolled out in 2012.

Australia became the first country to introduce the measure and it is currently being challenged in the World Trade Organisation.

Labor successfully pressured the Coalition into announcing its own ban on accepting donations from tobacco companies during the last election.

The Opposition has attacked Mr Christensen's comments supporting decriminalising marijuana.

"They are clearly not the same thing and Mr Christensen should know better," said the Opposition's health spokeswoman Catherine King.

Ms King called on Prime Minister Tony Abbott to reassure the community that the Coalition was not planning to decriminalise cannabis use.

"Unless the Government is happy to have Coalition MPs freelancing on drug policy, his comments should be clarified."