Sturgeon vows to lead opposition against Tory cuts and attack on human rights

Her party would "challenge a Tory agenda that lacks legitimacy in Scotland - and help the cause of progressive politics across the UK," she said.

David Cameron has made a new Scotland Bill a priority in order to translate the work of last year's Smith Commission on more devolution into reality and deliver on the pre-referendum 'vow' by the three Unionist parties.

However there are concerns that many of the draft clauses published to date are inadequate, and fail to turn the Smith recommendations into practical law.

Last week, the cross-party Holyrood committee looking at the draft clauses highlighted a number of shortcomings.

The First Minister said a key test of the UK Government's "good faith" would be whether the Scotland Bill lived up to both the spirit and letter of Smith.

She said: "The SNP's priority is ending austerity, and the damage it does to people's lives - the Tory government's priority is ending human rights, and the opportunities for fairness they offer ordinary men and women. For example, it was the Human Rights Act that enabled people to go to court in this country to challenge the grossly unfair bedroom tax.

"To scrap the Human Rights Act would be an appallingly retrograde step."

The Tories want to replace the HRA, which incorporates the European Convention on human rights into UK law, with a British 'bill of rights'.

However the ECHR is embedded in devolution through the 1998 Scotland Act which created Holyrood, and removing it would ordinarily involve Holyrood's consent.

Westminster could, in theory, repeal the HRA without Holyrood's approval, but it would cause a constitutional and political storm, and prompt calls for a second referendum.

Sturgeon added: "SNP MPs will work across party lines at Westminster to defeat the Tory government on the Human Rights Act - and the SNP Government will invite the Scottish Parliament to refuse legislative consent to scrap it, given the strong devolved dimension."

The First Minister also said she would press Cameron to go beyond the Smith Commission to give Holyrood more powers "for which half of Scotland's electorate and 56 of the 59 Scottish constituencies voted. The people of Scotland have spoken, and Westminster has a democratic duty to listen."

Dr Eilidh Whiteford, the SNP's Westminster spokesperson on social justice, said the party would also press for a brake on welfare cuts which would put more people into poverty.

She said: "With Labour all over the place and each of their leadership candidates seemingly getting ready to race even further to the right, the SNP is the only real opposition to unfair Tory cuts in the House of Commons - and people in Scotland can be assured that we will fight George Osborne and David Cameron's plans to impose more cuts on disadvantaged people at every turn.

"The UK Government's continued commitment to the savage welfare cuts that are inflicting such hardship underlines why they can't be allowed to take decisions on social security on Scotland's behalf any more.

"People in Scotland gave the SNP an unprecedented democratic mandate to put an end to the cuts agenda which is hurting people across our communities - and we will use this to work with progressive allies both inside and outside of Westminster."

Another key element of Wednesday's speech will be Cameron's plan for an in-out referendum on the UK's membership of the European Union.

It also emerged yesterday there will be new measures to speed up adoption, with council services merged to allow children to be matched with families sooner.

A spokesman for the Ministry of Justice, where Michael Gove is leading the HRA plan, said: "The government was elected with a manifesto commitment to replace the Human Rights Act with a British Bill of Rights. Ministers will be discussing their plans on this and making announcements in due course."