A van painted with a slogan that Ad Standards condemned for its sexually explicit language has been spotted in Cairns in far north Queensland, with one tourist describing it as "vile".

Key points: A camper van decorated with sexually explicit language was spotted in Queensland

A camper van decorated with sexually explicit language was spotted in Queensland Despite changes to state laws, no action can be taken because the vehicle is registered in South Australia

Despite changes to state laws, no action can be taken because the vehicle is registered in South Australia The loophole has prompted calls for a national approach to legislation

John, who asked his last name to be withheld, said he was walking along the Cairns Esplanade while holidaying with his partner this week when they saw the slogan, "Am I still a virgin if I take it up the s*****r?".

"We were just absolutely awestruck to think that in 2018 someone would have that slogan written on a van that anybody can see," he said.

"There are lots of tourists to Cairns from overseas and what do they think, that we're [Australians, are] all a bunch of rednecks?

"It's just so vile. It's not right."

Laws were passed in Queensland and Tasmania in 2017 in response to complaints about offensive slogans on vehicles.

Under the laws, if the Advertising Standards Bureau (ASB) upholds the complaints they are referred to the Department of Transport and Main Roads, which can cancel the offending vehicle's registration if the slogans are not removed within 14 days.

A complaint about the same van John found offensive was upheld by the ASB in April this year, but the van is yet to be taken off the road because it is registered in South Australia.

"The Panel noted the transport advertisement featured the words 'Am I still a virgin if I take it up the s*****r?'," the report stated.

"[It] noted the reference to 'taking it up the s*****r' and considered that this is an explicit reference to a sexual act [and] it had previously dismissed instances of the word 'shit', but the clear sexual context in this case was too strong for a broad audience."

Both sides of politics push for national action

Queensland Main Roads Minister Mark Bailey said, without a national approach, it was hard to keep vans with slogans that have breached the Ad Standards Code of Ethics off the road.

He said the laws passed in Queensland and Tasmania should be passed nationwide.

"Our Government has targeted sexist, misogynistic and inappropriate slogans on vehicles through registration cancellations," he said.

Minister for Main Roads and Road Safety Mark Bailey says all states need to get on board with a ban. ( ABC News: Patrick Williams )

"Unfortunately, if a vehicle is registered in another state, there is no jurisdiction for us to take action, other than to continue our advocacy to other states to follow our lead and get these offensive vehicles off our roads.

"I'll gladly write to [South Australian Transport Minister Stephan Knoll] again and attach a photo of this nasty vehicle, once more asking his Government to mirror our legislation and partner with us to take discriminatory vehicles off the roads."

Queensland Opposition Main Roads spokesman Steve Minnikin called for the slogans to be discussed at the forthcoming Council of Australian Governments meeting on December 12.

"The van is absolutely disgusting … and parents of young children would be appalled," he said.

Some people are taking the matter into their own hands. ( Flick: Shellie Evans )

Ad Standards call for government support

Mr Minnikin said Ad Standards was doing its job, but it came back to governments to work together.

"We'd urge the State Government to work with the Federal Government to stamp out this problem," he said.

Differences in state laws: Queensland and Tasmanian State Governments passed laws in 2017 in response to complaints

Queensland and Tasmanian State Governments passed laws in 2017 in response to complaints The laws allow governments to deregister vehicles if the Ad Standards Community Panel decides they breach of the code of ethics

The laws allow governments to deregister vehicles if the Ad Standards Community Panel decides they breach of the code of ethics Those laws do not apply in other states and territories

Those laws do not apply in other states and territories The Queensland Opposition says laws will not work if they are not passed on a national level

"Wicked Campers have a lot to answer for as a company. There is a line and I believe they have well and truly crossed it yet again."

An Ad Standards spokesperson said they were pushing for a national approach to help them enforce rulings.

"Ad Standards is liaising with the Federal Transport Minister seeking assistance with placing an item on the National Road Transport Minsters' forum seeking national consistency in relation to assisting with [our] determinations," they said.

Wicked Campers Australia has been contacted by the ABC for comment.