Facebook CEO Mark Zuckerberg says the company will bring more transparency into its political advertisements, responding to criticism that it has not done enough to prevent the manipulation of elections.

The National Party have lost an appeal to the Advertising Standards Authority over a Facebook ad ruled misleading and have been forced to delete it.

But one of the original complainants says that the fact it took seven months for the ad to be taken down is not good enough.

The Facebook ad from the National Party concerned the Government's proposed "feebate" scheme and vehicle efficiency standard and was released in mid-2018.

Screenshot The ad ruled misleading.

The ad claimed that because the efficiency standard could result in penalties for car importers who don't meet an average emission standard across their entire fleet, those costs could be passed on to consumers in higher car prices.

This, combined with the "feebate" scheme which applies subsidies for some cars by imposing penalties on others, could turn into a $6000 fee on vehicles, the ad argued, noting that Associate Transport Minister Julie Anne Genter had described the policy as imposing a "small fee".

"What hope does an ordinary Kiwi have for getting some relief from taxes and costs if the people running the Government think $6000 is a small fee" the ad asked.

After two complaints the Advertising Standards Authority (ASA) ruled that the ad was misleading and "likely to confuse or deceive consumers" - because it was not substantiated that the efficiency standard would necessarily lead to higher prices.

"Having reviewed the LEV consultation document, the Complaints Board said there was no evidence the Clean Car Standard scheme would translate to a cost for the consumer as the advertisement claimed," the board wrote.

National appealed the decision and did not remove the ad from Facebook during the appeal process, arguing the ad raised "serious concerns of a high public interest".

The argument essentially boiled down to the National Party assuming that the emissions standards set by the Government would not be met by importers, meaning those importers would have to pay a penalty that was then passed on to consumers.

But the separate appeals board rejected this argument and upheld the decision to declare the ad misleading unanimously.

The board said the advertisement "made a blanket factual statement, without any qualifications, which required substantiation" and that the substantiation provided in the appeal did not support the consumer takeout from the advertisement - that ordinary Kiwis would face a $6000 fee when buying a new car.

Complainant Adam Currie said it had taken far too long for the decision to happen, meaning the ad was live for seven months.

"I made the complaint in July last year - the original decision was not made until the September 9, and now the ASA is finally forcing the advertiser to remove the ad - after it's had seven months to mislead the public," Currie said.

"By this timeline, an ad reported today would be allowed to run until the beginning of advance voting for this year's election."

"It's shameful to allow the public to be misled for so long, but it's important that people are aware that National is putting out ads that are factually misleading."

ASA chair Hilary Souter told Stuff the body generally expected ads to be removed during the appeal process if a complaint was upheld against them.

She has also said the ASA expect to set up a rapid-response system for the election period.

National leader Simon Bridges said his party reserved the right to not delete ads during appeal processes, saying the ASA had "no legal basis" for its opinion that those ads should be taken down.

He said he stood by the ad but he respected the decision by the ASA.

"At the end of the day we thought we were right, but we respect the decision," Bridges said.

Green MP Golriz Ghahraman said the fact National had resorted to lies proved how strong the policy was.

"Kiwis deserve better than deliberately false and misleading political advertising. We've seen how this kind of cynical political campaign, especially shared on social media, has perverted democracy elsewhere in the world," Ghahraman said.

"It's sad that this is the way the National Party is going."