A strike at Boeing has forced Ryanair to make changes to its autumn operations because of problems with taking delivery of new aircraft.

Ryanair said yesterday that the strike would lead to "minor modifications" to its flight schedule in September and October.

It also left open the possibility of further changes to its schedule if the Boeing strike looks like running into November. If this appears likely, the airline will tell its passengers about changes at the start of October. This could lead to a temporary freezing in capacity at Ryanair.

The airline's problem is that it was expecting to get seven new aircraft from Boeing in September and October, but will probably now receive them no earlier than November or December.

As a result, it has decided to continue flying three older aircraft that were due to be retired in October.

It has also "amalgamated" about 200 flights in October, thus changing some flight times as capacity is shifted around the Ryanair network.

The airline said this would affect less than 1 per cent of its flights and would have an "immaterial" financial impact.

Ryanair also said it would launch its new bases at Liverpool and Pisa as planned, helped by a new aircraft delivered early by Boeing at the start of this month.

The airline expects to "liaise closely" with Boeing as the strike at the US company evolves.

Boeing has a long history of industrial relations problems, famously enduring a 69-day strike in 1995.

Shares in Ryanair closed unchanged at €6.80 last night.