SNP activists will take part in a major anti-fracking demonstration at their party's own conference this weekend, as pressure mounts on Nicola Sturgeon to ban the controversial gas extraction technique.

A coalition of organisations, including a grassroots SNP campaign group, are planning a protest which will see demonstrators create a human chain around Glasgow's SECC, where the party's spring showpiece is taking place, and call for a total fracking ban in Scotland.

The move, planned for the first day of conference on Saturday, is likely to prove a major embarrassment to ministers, with activists calling on their own party to adopt a position now backed by Scottish Labour, the Liberal Democrats and the Greens.

A refusal to rule out allowing fracking once a current moratorium ends has caused unease among many in the party grassroots, with a significant number of members strongly opposed to it. Activists were also angered when party power brokers blocked a co-ordinated bid to allow members to discuss a fracking ban, potentially allowing them to force through a policy change, in the conference hall.

SNP activists will instead now have the chance move outside the venue to voice their opposition to fracking and call on Ms Sturgeon and her energy minister Fergus Ewing to take a tougher stance.

A source within the SNP Members Against Unconventional Oil and Gas (SMAUG) group said: "The idea is that it'll be hands around the conference, with the intention of demonstrating the feeling within the party.

"It'll be a broad alliance of SNP voters and other groups to try and keep the issue on the radar. It will hopefully be a big, friendly and noisy event."

While Ineos, the chemical giant that wants to establish a fracking industry in Scotland, took a stall at the SNP's main conference last autumn in a bid to win over members it is understood that the firm will not have a presence at the Glasgow event.

Last week, the company warned that the country will pass up the chance of an economic lifeline that could compensate for dwindling offshore oil and gas reserves if fracking is not given the go-ahead.

The intervention came shortly after the First Minister revealed she is "highly sceptical" of fracking, following Labour leader Kezia Dugdale's move to say her party would go into May's election calling for a ban and challenging the SNP leader to do the same.

A moratorium on fracking, which sees a mix of water, sand and chemicals pumped underground at high pressure to fracture shale rock and release trapped gas, is due to remain in place until next year while research and a public consultation is carried out.

Ms Sturgeon, who has vowed to take an evidence-based approach to fracking, has refused to spell out what her decision will be should the results of the research back up previous Scottish Government studies which found the technique can be carried out safely if properly regulated.

She is likely to face increasing calls to clearly set out her stance as the Holyrood elections approach with fracking looking set to become a major campaign issue.

Sarah Boyack, Labour's environment spokeswoman, said: "People have a right to know what the SNP’s policy on fracking actually is. The SNP are only committed to a temporary freeze on fracking, not an outright ban. It’s time for the SNP to say where they really stand on fracking."

Organisers of the protest, which will also include non-party political campaign groups such as Our Forth and South Lanarkshire Against Unconventional Gas, hope to recreate scenes last October when hundreds of people linked arms across the Forth Road Bridge to oppose plans to ignite coal under the sea bed.

A spokesman for the SNP said: "We are taking a sensible and careful approach to fracking, which is why we have put a moratorium in place meaning no fracking can take place in Scotland - something that has been welcomed by campaigners and environmental groups."