A ban on plastic bags introduced by the City of Fremantle is under threat by an Upper House MP who wants to overturn it.

Liberal MP Peter Katsambanis has moved to disallow the ban on non-biodegradable plastic bags introduced by the port city last year.

Fremantle is the first local government in Western Australia to ban plastic bags.

The council had tried to implement the ban in 2013, but the move was struck down by the State Government.

Mr Katsambanis, the member for the North Metropolitan region, said the use of plastic bags was not an issue that should be left up to individual local governments.

"Unfortunately the City of Fremantle doesn't seem to have grasped the fact that the Parliament has already spoken," he said.

"And in a lot of ways by moving this new local law it seems as though they are thumbing their nose at the Parliament."

He said the ban would create unnecessary confusion and work for local business.

"It would be crazy for a shopkeeper who has a shop in Fremantle and another shop in East Fremantle to have two sets of rules apply in relation to plastic bags," Mr Katsambanis said.

But Greens member Robin Chapple has labelled Mr Katsambanis' move to disallow the regulation as "draconian and almost neolithic".

"This is a very progressive local law," Mr Chapple said.

"In other places around the world where it's been introduced it's had major impacts on landfill and on plastic bags floating around in the environment.

"It's almost going back to the dark ages."

The City of Fremantle issued a statement expressing disappointment in the motion.

"There are several other local government authorities, both in Western Australia and in other parts of the country, who are eagerly awaiting the outcome before they moved to implement similar laws so there will be a lot of interest in this decision," the statement said.

"We will be calling on these like-minded councils and other community groups and supporters to lobby the State Government, to make a sensible decision on a matter which has far reaching and serious implications."