Global airlines started 2018 by suffering the slowest annual rise in demand in nearly four years.

The rise in traffic of just 4.6% in January was attributed by Iata to temporary factors including the later timing of the Lunar New Year in 2018 as well as less favourable comparisons with the strong upward trend in traffic seen in late 2016 and early 2017.

The impact of the later Lunar New Year-related travel period holiday represented around two-fifths of the slowdown.

January capacity rose 5.3% and the load factor slipped half a percentage point to 79.6%.

Iata director general and chief executive Alexandre de Juniac said: “Despite the slower start, economic momentum is supporting rising passenger demand in 2018.

“That said, concerns over a possible trade war involving the US could have a serious dampening effect on global market confidence, spilling over into demand for air travel.”

He added: “Aviation is the business of freedom. It liberates us from the constraints of geography, distance and time, enabling us to lead better lives; and it makes the world a better place.

“For the business of freedom to grow the benefits it generates, we need borders that are open to trade and travel, and infrastructure to support the demand for connectivity.

“Governments have the main role to play in these areas by preserving the benefits of global commerce and ensuring adequate airport and airspace capacity to cope with an expected doubling of demand by 2036.”