Britain's airports are warning travellers they could face major delays Thursday when civil servants and teachers plan to take part in a nationwide strike.

BAA, which runs Heathrow, Stansted, Edinburgh, Glasgow, Aberdeen and Southampton airports, made the statement Wednesday.

Nearly three quarters of a milllion teachers and civil servants are planning to walk off the job Thursday due to a dispute over pensions.

Four trade unions voted to strike on June 30.

Prime Minister David Cameron made a final plea Tuesday to persuade the workers to abandon the strike.