SSP, the travel concessions operator, has reported UK like-for-like sales growth of 1.9% for the six months to 31 March but said strike action has hit sales at railway stations.

Revenue in the UK increased by 3.8% on a constant currency basis to £365.2m, with net contract gains of 1.9%.

The group said like-for-like growth was particularly strong in the air sector, driven by continued growth in UK airport passenger numbers and increased spend per passenger.

However, the group said the rail sector saw weaker trading, notably in London stations, principally as a consequence of lower passenger dwell times and the impact of industrial action.

Underlying operating profit for the UK increased by 11.3%, on a constant currency basis, to £29.7m, while underlying operating margin increased by 60 bps to 8.1%.

The group said: “Growth was driven by good like-for-like sales growth in the air sector, and from the implementation of our strategic initiatives, particularly gross margin optimisation, where the UK continues to lead the roll out of many of our retailing and procurement programmes. However, the UK business faces on-going inflationary pressure on food and drink costs from the impact of weaker Sterling, and on labour costs due to the increases in the National Living Wage and the National Minimum Wage.”

On a group-wide level – revenue of £1.07bn was up 8.1% at constant currency; 19.6% at actual exchange rates.

Like-for-like sales grew 2.9%, which SSP said was driven by air passenger travel and retail initiatives.

Underlying profit before tax was up 49.6% to £34.7m.

Chief executive Kate Swann said: “SSP has delivered another good performance in the first half of 2017 and we continue to make progress on our strategic initiatives. Constant currency operating profit was up 25% driven by good like-for-like sales growth and further operational improvements. We have had a particularly strong period of new contract openings, growing our presence across the world particularly in North America and the Asia Pacific region. The pipeline is robust and we are pleased with the new contracts won in the first half. Our Joint Venture in India has started well and we are encouraged by the progress we are making there.

“Looking forward, the second half has started in line with our expectations and whilst a degree of uncertainty always exists around passenger numbers in the short term, we continue to be well placed to benefit from the structural growth opportunities in our markets and our programme of operational improvements.”