While many cities on the American west coast have banned plastic grocery bags, Vancouver Mayor Gregor Robertson says the provincial government is holding him back from taking the same step.

Making Vancouver the greenest city in the world by 2020 has been one of Robertson's election promises.

But last week Los Angeles, the so-called smog capital of the U.S., out-greened the Canadian city when it passed a motion against plastic grocery bags. San Francisco, Seattle and Portland have already implemented similar bans.

"Unfortunately, Canadian cities don't have the option to ban plastic bags; the provincial government makes that decision or they could enable us. So we would like the B.C. government to enable Vancouver and other cities to make that decision," Robertson told CTV News.

If it were up to Robertson, Vancouver would already have a ban on plastic grocery bags.

"Hopefully, we have the ability from the B.C. government to go forward on this soon. I would like to see it happen this year while this government is in place, but certainly we'll be calling on it and asking them to take that action step," Roberston said.

"We're looking at pushing harder on the province to give us this power," he added.

Provincial officials say allowing such a ban would require a change to the Vancouver Charter and new provincial legislation.

However, some Vancouver grocers have taken their own action against the use of plastic bags. Greens Organic and Natural Market doesn't provide them and IGA supermarkets credits customers three cents for bringing their own bags.

Stong's Market offers plastic bags for free, along with cloth and paper options, but doesn't oppose a ban.

"I think that's the way that eventually Vancouver will go, and if it happens here we'd support it. But right now we got to provide customers with what they want, so hence the options," assistant manager Dane Robertson said.

In 2014, provincial legislation will require plastic bags to be fully recyclable.

With a report from CTV British Columbia's Shannon Paterson