NICOLA Sturgeon yesterday said a resurgent SNP could anchor an alliance of anti-austerity MPs at Westminster after the General Election, as she rounded off an extraordinary week with the largest party rally of modern times.

After making history over consecutive days by becoming Scotland's first woman First Minister and unveiling the country's first gender-balanced Cabinet, Sturgeon appeared before almost 12,000 SNP supporters at the Hydro arena in Glasgow.

The ease with which she filled the venue - faster than Rod ­Stewart, Kylie Minogue or Lady Gaga - confirmed her rock-star status. Warm-up acts Eddi Reader, Lou Hickey and the Red Hot Chilli Pipers emphasised the point.

During the two-hour session, the SNP's membership, which stood at 25,000 before the referendum, rose from 90,263 to 92,197.

A target of 100,000 members by next May's General Election now seems sure to be reached within days, meaning one adult in 50 in Scotland will soon be an SNP member.

"It proves that right here, now, right now, democracy rocks," Sturgeon said. The crowd responded by holding aloft hundreds of giant SNP-branded foam hands.

The First Minister repeated her promise not to put the Tories into power in the event of a hung parliament next May, and said the SNP would demand the non-renewal of Trident as a condition of supporting a Labour administration.

She said the SNP would build alliances with "other progressive forces" on a case-by-case basis to further social justice and bring about an end to the UK's "austerity agenda".

With polls suggesting the SNP will boost its tally of six MPs next May, she said the party would work with fellow progressives to ensure fairness for all the regions of the UK.

She named the Welsh nationalists and the Greens as likely partners in a new voting bloc, and said: "The old Westminster system doesn't work for Scotland, we know that all too well.

"But you know what, it doesn't work for many other parts of the UK either. So when we send a strong team of SNP MPs to Westminster, we will seek to build alliances with progressive forces across these islands."

She went on: "My aim is that the SNP wins the General Election in Scotland, and there is every prospect of a hung parliament at Westminster.

"In these circumstances, our constructive approach is that the SNP will seek common cause in a balanced parliament with ­progressive forces across the regions of England, Wales and Northern Ireland to rebalance the UK in political and economic terms.

"Scotland can play a leading role in this process, and bring an end to the failed austerity economics which has gripped the frontbenches of the Tories, Labour and LibDems.

"In turn, we can build wider support for some of Scotland's priorities - such as achieving the powers we were promised by the No campaign, and preventing a new generation of Trident nuclear weapons being dumped on the Clyde."

With Plaid Cymru and the Greens led by Leanne Wood and Natalie Bennett respectively, she added: "Westminster be warned, the age of female politics is here and it's not going away."

Asking Labour supporters to "lend" their vote to the SNP in May to achieve greater social justice, Sturgeon said: "Every SNP MP we elect will turn up the pressure for the delivery of substantial new powers.

"A vote for the SNP is a vote for Scotland's interests. It is as simple as that."

The event included an appearance by former SNP leader and First Minister Alex Salmond, who described his 44-year-old successor as "the most brilliant young woman in Scottish politics".

SNP deputy leader Stewart Hosie MP also looked ahead to the General Election as a chance to hammer Labour at the polls and end austerity. Referring to the energy of the ­referendum campaign, he said: "We need to harness and turn that desire for change into votes for change."

But the day belonged to the First Minister. In a speech punctuated by standing ovations, Sturgeon said she was convinced independence would happen "one day", but offered no date.

Sturgeon will announce her first legislative programme to Holyrood on Wednesday.

"As First Minister I shall govern for each and every part of this great country of ours, work to empower our great cities, renew and reinvent our towns and to bring a new spirit to all of our communities," she said.

"Land reform will mean much-needed change in the Highlands and other rural areas.

"For all there will be radical social protection, a huge increase in free childcare helping parents return to work and giving their kids the best start in life. New funds for our NHS, mitigation of the hated 'bedroom tax' and a pledge that wherever and whenever we can, this party, this Government, will work to protect the poor, the disabled and the vulnerable."

Before the gathering wound up with Dougie MacLean leading the crowd in his hit song Caledonia, Sturgeon said: "This is a great time to be alive in Scotland. Our ­democracy is more vibrant than probably anywhere else in Europe."

She said new powers coming to Scotland after the Smith Commission on greater devolution would help Scotland unlock its potential in part,

But, she said, there was only one "master key which unlocks all of the doors to a better, fairer, greener and more prosperous Scotland and that key is independence. History is with us, the wind is set fair. We will build the Scotland our people deserve, let us get on with that job."

Tory MSP Alex Johnstone said the public wanted change from "the ego-led era of Alex Salmond". He added: "When Scotland's new First Minister is strutting around the country like some kind of pop star, the public are right to question why she is not concentrating more on the day job." Scottish Labour declined to comment.