London: Thousands of UK schools and offices remained closed on Wednesday as one of country's biggest public sector strikes in decades got underway here that also threatens to affect the airport passenger traffic.
The 24-hour strike is expected to disrupt hospitals, courts, job centres, driving tests and council services, such as libraries, community centres and refuse collections.
Teachers and heads are taking to the picket lines, affecting almost three in four schools, according to early Government figures. However, it is feared this number could rise.
Airport officials expected delays at immigration counters later during the day at Heathrow and other airports in Britain.
There were no reports of delays at airports so far, but chief operating officer Scott Stanley at Gatwick Airport said: "Whilst passengers have so far not experienced delays at the border zones we do expect delays to occur at some point on Wednesday as the rate of arriving flights increases".
Passengers, who arrived on flights at Heathrow this morning, said they were through immigration formalities without any delay.
Many flights from India arrive in the second half of the day, when delays are expected.

The call for strike has led to Air India cancelling four flights to London scheduled for on Wednesday and Jet Airways issuing advisory asking passengers travelling to the UK to rebook their flights to avoid any inconvenience.
BAA, which runs Britain's airports, said last night: "At this stage, we believe that immigration queues for non-EU passengers could be contained to within two to three hours".
The strike has been called by public sector employee unions against changes to pension rules and job losses.

The strike is said to one of the biggest in a generation, and is expected to see over 1,000 demonstrations across Britain.
Speaking from Brussels, Chancellor George Osborne said, "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".
He added, "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 on Wednesday, not seeing these strikes".
Dave Prentis, general secretary of union Unison, said industrial action by his union was rare but public sector workers "were annoyed".
Millions of workers - mainly low-paid women - were being unfairly affected by changes to pensions, he said. The Department for Education said it believed that more than half of England's 21,700 state schools (58 percent) are closed, with a further 13 percent partially open.
About 13 percent are operating as normal, while the rest (16 percent) are unknown.