UNION staff and opposition parties have attacked The Tories' plans to crack down on trade unions.

The Trade Union Bill, which was published yesterday, will criminalise unlawful picketing, make it harder for Labour to get cash from trade unions and make it trickier to strike legally.

It also means a legal strike will only be able to happen if at least 50% of people asked to strike vote in a ballot, and at least 40% vote in favour of the action.

Scottish Trade Unions Congress (STUC) general secretary Grahame Smith described the bill as "vindictive, unfair and unnecessary" and said it attacked the human rights of workers to withdraw their labour.

He added: " It is a Bill that tramples over our civil liberties and should be of concern not just to workers but to everyone who values the right to peaceful protest.

"This Bill starts from the false premise that unions are bad and their activities need to be curtailed."

He said the bill contradicted the position in Scotland of unions working with employers and the government to tackle " low pay, job insecurity, inequality, underemployment and skills shortages to improve productivity and economic success and to reduce poverty."

He added: "The call for the devolution to Scotland of employment law and trade union regulation will only grow as a consequence of the current attack."

Glasgow Unison's branch secretary Brian Smith mimicked the STUC's concerns and added: "In terms of the balloting thresholds it presents an issue of democracy.

"If you applied those thresholds you wouldn't have elected politicians.

"The state shouldn't get involved in how trade unions internal processes runs, that's what members do."

Scottish Labour accused the Tories of coming up with a "divisive piece of legislation" that did nothing but gag trade unions.

Siobhan McMahon, the party's Youth and Women's Employment spokeswoman said: "This Bill is the latest in a long line of attempts by the Tory Government to stifle reasonable democratic scrutiny, protest and challenge – put simply, this is another Gagging Bill.

“This Bill does nothing to tackle the pressing national challenge our public services, businesses and industries alike are facing; that of addressing Britain’s productivity gap and skills shortages."

The SNP MP Hannah Bardell, the party's fair work and employment spokeswoman described the legislation as Dickensian and said: "The SNP are determined to stand up for social justice and progressive policies in this parliament for the whole of the UK. The Tories have a wafer thin majority and were elected with less than 25 per cent of the total possible popular vote.

"Ironically, under their own ‘40 per cent’ plans for the trade unions, the Tories wouldn’t even be in government – if David Cameron wants to rig the rules for others, he should apply the same standards to himself."