Up to two million public sector workers are staging a strike over pensions in what is set to be the biggest walkout for a generation.Schools, hospitals, airports, ports and government offices will be among sites disrupted, as more than 1,000 demonstrations are due across the UK.
The chancellor urged more talks, saying strikes would not achieve anything.
Unions object to government plans to make their members pay more and work longer to earn their pensions.
The strike has impacted:
- About 2,700 schools out of 21,700 are open in England says the BBC's education correspondent Gillian Hargreaves.
- The Department of Education says it is expecting 13% of state-funded schools in England, including academies and free schools to open and 13% to be partially open. The status of 16% of schools is unknown.
- Plane arrivals and take-offs at Britain's two biggest airports - Heathrow and Gatwick - are largely unaffected with only a few cancellations of inbound transatlantic flights to Heathrow.
- Heathrow operator BAA, and its busiest carrier, British Airways, have both reported near-normal services, with queues at immigration no longer than usual.
- At Heathrow, the 10 EU UK desks at Terminal 3 immigration are being manned by mix of home office staff and police officers who have been trained. Five non EU desks are open as airport sources suggest immigration controls are at two thirds of normal staffing levels
- In Northern Ireland, no bus or train services will be operating and two thirds of schools and colleges will be closed.
- About 300,000 public sector workers are set to go on strike in Scotland while 170,000 workers in Wales are to take action
- 'Negotiating table'
Speaking from Brussels, Chancellor George Osborne told BBC Breakfast: "The strike is not going to achieve anything, it's not going to change anything. It is only going to make our economy weaker and potentially cost jobs.
"So let's get back round the negotiating table, let's get a pension deal that is fair to the public sector, that gives decent pensions for many, many decades to come but which this county can also afford and our taxpayers can afford.
"That is what we should be doing today, not seeing these strikes."He added that without making difficult choices about dealing with the UK's debts the country "would be bankrupt".
Labour leader Ed Miliband said he had "huge sympathy" for people whose lives are disrupted by the strike.
But he said he was "not going to condemn the dinner ladies, nurses, teachers who have made the decision to go on strike because they feel they have been put in an impossible position by a government that has refused to negotiate properly".
Shadow chancellor Ed Balls told BBC Breakfast the pensions row should have been resolved by the government.
On Tuesday night, shadow chief secretary of the treasury, Rachel Reeves, told BBC's Newsnight that Labour did not support the industrial action.
"We do not support the strike because a strike is a sign of failure," she said.
Earlier on Tuesday, union leaders reacted angrily to Mr Osborne's Autumn Statement announcements of a public sector pay cap of 1% for two years, as well as bringing forward to 2026 the rise in the state pension age to 67.