NICOLA Sturgeon is to hammer out opposition to a law that would curtail trade union rights in a face-to-face meeting with David Cameron in Downing Street.

The First Minister made the announcement at a rally where she united with Labour leader Jeremy Corbyn to oppose the reforms and just hours after an SNP bid to block the legislation was scuppered by Holyrood's Presiding Officer.

Following calls to "send a strong message" to the Westminster Government, Ms Sturgeon said: "I'll do better than that. I'm going to meet the Prime Minister in Downing Street and will take the message from here that Scotland opposes your anti-trade union Bill."

The First Minister also told delegates in Glasgow that the Scottish Government would "never employ agency workers to undermine strike action".

Later at thye rally Mr Corbyn said: "The reality is this is likely to become law. The question is who to we fight and inspire ourselves to resist it."

Claiming the Trade Union Bill was part of the Conservative's "austerity politics" he also called on the Scottish Parliament to use whatever enhanced powers it has to mitigate against omcoming cuts. 

Earlier in the day the Scottish Government had insisted that aspects of the Trade Union Bill impacted on devolved functions and therefore the Edinburgh parliament should be required to consent to the legislation.

However, presiding officer Tricia Marwick, elected as an SNP MSP before taking on the politically neutral role, has sided with the UK Government in the unprecedented row.

She deemed a legislative consent motion, which was proposed by the Scottish Government and would have added weight to its claims that the measures should not apply in Scotland, was "not competent" as the powers were within Westminster's remit.

Over 1,000 people from trade unions and various political parties attended last night's rally at the Glasgow Royal Concert Hall organised by the Scottish Trades Union Congress (STUC).

Appearing on stage over two hours before Mr Corbyn, the First Minister said: "This Bill should not pass without the consent of the Scottish Parliament. We lodged a legislative consent memorandum to start that process but unfortunately that has been blocked.

"But we will do everything we can to ensure our democratically elected parliament has a say. This impacts on the devolved responsibilities and the Scottish Government as an employer.

"We will do everything we can to ensure that this Bill does not succeed if it is passed."

Ms Marwick rejected the argument that proposed measures including deductions from pay for union subs and wage arrangements for agricultural workers directly impinged on Holyrood's responsibilities.

In a letter to Fair Work Secretary Roseanna Cunningham, Ms Marwick said: "Having given the matter careful consideration and applying the tests set out in the rules, my view is that the Parliament's legislative consent is not required and it is not competent to lodge a legislative consent memorandum."

Ms Sturgeon's spokeswoman said that the rejection demonstrated the need to devolve trade union powers so that the Scottish Government could "properly conduct employee relations".

The Trade Union Bill would introduce minimum turnouts in strike ballots, allow employers to use agency workers to replace striking staff and end the so-called check-off system for collecting union subs direct from a salary. Strike organisers would have to wear armbands to identify themselves on pickets.

The stand-off with Westminster raises the prospect of a constitutional crisis, which could arise should the devolved administration refuse to recognise legislation in an area that it does not have responsibility for.

At last night's rally, Grahame Smith, the STUC general secretary, said the organisation would support any body that refused to comply with the Bill, should it become law.

He added: "It is inevitable that if this Bill is implemented it will bring unions into conflict with the law and bring the police, lawyers and judges into industrial relations as never before."

Mr Corbyn added: "The Tories want to sell off most public services and public assets so we have to stand up against this trade union bill. And I congratulate those councils whiuch are taking a stand against this bill."

Scottish Conservative MSP Murdo Fraser said: "The SNP now have egg on their faces after trying to play constitutional games in relation to what clearly is a reserved matter for the UK Government."