Ministers are considering moves to crack down on the unions amid fears of a wave of crippling industrial action over public sector cuts, according to reports.
Business Secretary Vince Cable and Cabinet Office minister Francis Maude are drawing up plans that could see an end to full-time union officials receiving taxpayer-funded salaries, according to The Sunday Telegraph.
They are also looking at the possibility of legislation imposing a minimum threshold on strike ballot turnouts before industrial action can be taken, the paper said.
The prospect of such a package, described as a "last resort" by a source, comes as relations between the Government and union leaders are turning increasingly bitter over plans to reform public sector pensions.
Prime Minister David Cameron is expected to make a speech defending the plans which will require public sector employees to work longer and, for most, pay more into their pension pots for often less attractive benefits.
His intervention follows a series of warnings from Cabinet ministers, including Dr Cable, about the likely consequences of union militancy.
Earlier this month the Business Secretary told the GMB's annual conference that pressure for a change to the strike laws would "ratchet up" if the unions caused economic damage with industrial action.
Chief Secretary to the Treasury Danny Alexander infuriated the unions last week by warning it would be a "colossal mistake" to reject the Government's offer on pensions, which he said was the best they could hope for.
However strikes will begin on Thursday when up to 750,000 teachers, lecturers, civil servants and other public sector workers take action and there are threats of further walkouts throughout the summer and autumn.
RMT general secretary Bob Crow yesterday said the unions were on the edge of "the biggest industrial confrontation in 80 years" and warned of the biggest counter-operation since Margaret Thatcher's government in the 1980s.
"We saw during the miners' strike what happens when the state and bosses' organisations mobilise against working people - checkpoints on motorways, banning orders, security service infiltration, collaboration with the right-wing press and repressive legislation designed to harass and undermine those prepared to stand up and fight for their livelihoods and their communities," he said.
"Behind the scenes, those same shadowy forces are working through the night to play out the same role in the months ahead."
Shadow cabinet minister Peter Hain accused the Government of "reckless and arbitrary" attacks on public sector workers.
"One of the things that's led to this situation is the Government's reckless and arbitrary attack on public sector pensions without being willing to negotiate," he told BBC1's Andrew Marr Show.
"I don't think political leaders, in opposition or in government, should either applaud strikes or condemn strikes.
"I think what we should be trying to do is resolve strikes."
Declining to urge people to go to work on Thursday, he added that they went on strike if they "really think they have got no option".
"Teachers and others are not strike-happy. What this government should do is withdraw their unilateral, reckless attacks on these workers and get round the negotiating table like everyone wants them to do."Reuse content