CONSERVATIVE ministers have signalled new laws could be introduced to make industrial action more difficult and that a public sector wage freeze could last until 2018 as one million state workers prepare to strike this week over pay.

Francis Maude, the Cabinet Office Minister, said the Tory Party was looking at whether or not there should be a minimum threshold imposed on union ballots before strike action and if ballots should be time-limited.

"That's a live issue, whether there should be a threshold in terms of turnout so that a ballot, where the turnout is below a certain level, should not get a valid legal mandate for strike action.

"But we should also be looking at whether there should be some rule that a mandate falls after a certain time. It can't be right that a union should be able to come back year after year based on a mandate that's several years old in order to call strike action that does inflict real harm," said Mr Maude.

He also made clear the UK Government was "not budging" on its changes to pay and pensions for public sector workers. The Minister insisted it would be "totally irresponsible" to reverse changes that made pay and pensions "affordable and sustainable".

Meanwhile, Mr Maude's Tory ministerial colleague Matthew Hancock, asked if public sector workers would ever get a real increase in their pay under a Conservative government, replied: "Well, we certainly hope to have the books balanced by 2018. I don't think it is the right time to let go of the public finances at all." The one per cent pay cap is due, at present, to last until 2016.

On Thursday, more than one million public sector workers are expected to take part in what could be the largest industrial action since the General Strike of 1926.

Those expected to strike include council staff, teachers, firefighters as well as civil servants across the UK. Further walkouts are planned for later in the year.

Mick Cash, acting general secretary of the Rail, Maritime and Transport union, said: "Reports that the Tories are planning to ban public sector strikes and ratchet up their anti-union laws are nothing new and will meet the fiercest resistance.

"The front line of defence against cuts and austerity is the organised working class and that is why the Tories and big business want to tighten the legal noose around our necks. "

Paul Kenny, leader of the GMB union, added: "Not a single MP has secured 50 per cent of those eligible to vote in their constituency. There are no proposals for changes even though the outcome of that vote has a lot more significance than workers voting for action for a decent pay rise."