Travel delays are expected tomorrow as public sector strikes, which will include hundreds of immigration and customs officers, begin.

Travellers are being warned that the walkout by Border Agency staff will bring disruption to UK ports and airports and are being advised to consider travelling on alternative dates if possible.

750,000 teachers and civil servants will begin a 24-hour strike tomorrow over planned pension changes they believe will mean they have to pay more and work longer hours.

Thousands of schools, job centres, tax offices and courts are expected to be closed or badly disrupted and, if UK Border Agency staff join the strikes, air travel will also be affected.

Jonathan Sedgwick, acting chief executive of the UK Border Agency, said: "We will do everything we can to minimise disruption and inconvenience to travellers but our priority will always be to ensure that the UK border remains secure."

Airport operator BAA, which runs Heathrow, Stansted, Edinburgh, Glasgow, Aberdeen and Southampton airports, said in a statement: "We have been informed by UK Border Agency that arriving passengers should expect delays at the UK border on Thursday as a result of industrial action by immigration officers.

"UK Border Agency are advising that passengers who can do so may wish to travel on other dates."

Travel delays is likely to start at different times in different ports and airports tomorrow as each location has different shift patterns. The level of disruption will also vary.

International rail terminals could also be affected, the Border Agency said, but it said that there were contingency plans for all border points.

Tomorrow’s public sector strikes will be on a huge scale and business leaders have warned that there will be a significant effect on the on business confidence and inward investment.

"Public sector pensions have long faced problems of affordability, and reforms to bring them into line with those in the private sector are essential," said British Chambers of Commerce director general David Frost.

"The reality is that our workforce is living longer, and pensions need to reflect this to be sustainable in the long term.

The closure of schools will mean many parents taking the day off work to look after their children.

Prime Minister David Cameron has said the strikes are unjustified, claiming the new pensions scheme is “fair”.

The public remains split, according to a YouGov poll published in The Sun which found that 40% supported the industrial action while 49% opposed it.

What services will be affected by the strikes?

  • Up to 85% of schools in England and Wales will be partially or completely closed
  • Many colleges and universities ill be severely disrupted
  • Courts and probations services
  • Customs and passports services at airports and ports
  • Jobcentres and tax and benefit offices
  • Driving test centres