Greens have unanimously backed a call for the Scottish Government to make its ban on fracking "legally watertight".

Mark Ruskell, the party's MSP for Mid Scotland and Fife, said outlawing the controversial practice "for good" would be the "biggest victory in the history of the Green movement in Scotland".

While the Scottish Government has said it will not permit fracking to take place north of the border, concerns have been raised that the ban is not a permanent one, and could be ended if there were a change of government at Holyrood.

Mr Ruskell told the Scottish Green conference in Edinburgh: "The Scottish Government is sincere in their intent to ban fracking but we call on them through this motion today to put the ban on a legal basis that can not be undone by the stroke of a toxic Tory pen or an Ineos court injunction.

"We are calling for a proper ban under the national planning framework alongside the use of oil and gas licensing powers."

He added: "We've got this far, let's now win it."

The process of fracking - or hydraulic fracturing - involves injecting water at high pressure into shale formations, fracturing the rock and allowing natural gas to flow out, with opponents raising environmental and health concerns.

But supporters, including the Scottish Conservatives, highlight the economic opportunities fracking could bring to Scotland with the North Sea oil and gas sector in decline.

First Minister Nicola Sturgeon has however maintained fracking is being banned in Scotland, ''end of story''.

When pressed on the issue at First Minister's Questions earlier this month, she said the Scottish Government proposal to use planning regulations to extend its moratorium ''indefinitely'' was the quickest and most effective way of taking action.

Ms Sturgeon said: ''Of course the ban on new nuclear energy in Scotland is also done through planning powers, that is exactly what we are proposing with the ban on fracking."

She added: "Fracking is being banned in Scotland, end of story. There will be no fracking in Scotland. I don't think that position could be any clearer.''