Members of the University and College Union (UCU) campaigns team make placards for Thursday's planned protest against government plans to cut public sector pensions, at their headquarters in London June 29, 2011. [Photo/Agencies]

LONDON - Britain's Conservative-led coalition faces a test of its determination to drive through its austerity programme when teachers and civil servants strike on Thursday over plans to reform public sector pensions.

Many schools across the country will remain closed and air passengers face delays when immigration officials join a walkout that could involve up to 750,000 workers.

The strikes, mirroring protests across continental Europe against government-imposed austerity, could be a taste of wider protests to come later this year over pensions, an area where public sector unions appear determined to fight their corner.

Prime Minister David Cameron has condemned the strikes as irresponsible, saying that talks between unions and ministers have not concluded.

Cameron argues that longer life expectancy means that public sector pensions must change to ensure that they are affordable.  The changes are part of government plans by 2015 to virtually wipe out a budget deficit that peaked at more than 10 percent.

Workers face higher contributions to their pensions and longer working lives. The proposals have hit a raw nerve at a time of wage freezes and job insecurity.

Union leaders claim their members are bearing the brunt of a financial crisis caused by rich bankers.

"It is hardly surprising that public sector workers are on strike today," said Brendan Barber, head of the Trade Union Congress (TUC) union body.

"They know that they are being asked to play an unfair part in deficit reduction. What adds insult to injury is that this is wrapped up in attacks on public service pensions as gold-plated, unreformed and unsustainable," he added.

British right-wing newspapers backed Cameron, head of the right-leaning Conservative Party, and the Daily Mail newspaper covered its front page with a "Defy the strike bullies" headline. The Telegraph highlighted the "generosity" of current public sector pensions on its front page.

Left-leaning newspapers the Guardian and the Mirror's coverage was more muted, perhaps highlighting the unpopularity of strikes among many private sector workers, who say they have already had to deal with tougher pension terms and see no reason why public sector workers should be protected.

Analysts say the protests are a test of the government's resolve after it retreated on plans to restructure the state-funded National Health Service following lobbying from the medical profession.

Markets, which have reacted positively to government deficit-cutting plans, would take fright at any sign of a climbdown over an issue like pensions.

Thursday's protests involve about one in eight public sector workers, but other unions are gearing up for stoppages later this year if talks break down.

Some Britons sympathise with the strikers but others say they are being unrealistic at a time when households have suffered their biggest fall in disposable income for more than 30 years.

"The state of the country is pretty bad, they are a bit too focused on themselves," said Michael Hayes, a railway manager from the London suburb of Chingford.