Flights to Poland accounted for almost 20% of the increase in passengers at UK airports last year, suggesting migrant workers are fuelling growth more than holiday traffic.

Total passenger numbers hit 241 million, a 2.4% increase on 2006, according to Civil Aviation Authority figures – less than half the 6% average growth rate since the 1970s, but in line with a slowdown that began in 2005.

The CAA attributes the decline to slowing growth in consumer spending, although it has also coincided with heightened security at airports.

Passengers to and from Poland made up one million of the 5.6 million rise in numbers in 2007, a 31% increase. No other destination came close to this growth rate – passengers to Italy were up by 6% and to Spain 1.8%.

Numbers to Ireland fell by almost 1%. But transatlantic passenger numbers were up from 21.7 million to 22.4 million following a fall in 2006, reflecting the favourable ­exchange rate of the dollar.

Domestic traffic fell almost 2% to 25.3 million, in line with a shift to rail travel and a ­greater choice of flights from regional airports.

The long-term trend towards regional departures continued, although growth at airports outside London also slowed. Regional traffic grew 2.9% year on year to 101 million passengers, while London traffic increased 2.6% to 140 million.

Heathrow continued to dominate with 68 million passengers – 28% of the total. Gatwick handled 14.6%, Stansted 10%, Luton 4% and London City just over 1%. ­Gatwick added one million passengers on 2006, and Heathrow, Luton and London City 500,000 each.

Manchester remained the busiest regional airport with almost 22 million passengers – 9% of the UK total. Birmingham and Edinburgh handled nine million each – under 4% – and Glasgow 8.7 million.

Just over half of passengers flew on UK-based carriers, and 30% on airlines based in the EU.