Ryanair has been threatened with legal action after announcing plans to cancel thousands more flights and suspend routes between Scotland and London.

About 400,000 passengers will be affected by cancellations between November and March.

Ryanair has already scrapped 2100 flights as a result of "messing up" pilots' holidays, costing the airline around £44m.

Many travellers were hours from departure or already abroad when they learned their flights had been cancelled.

The Civil Aviation Authority (CAA) has said Ryanair "persistently misled passengers with inaccurate information" and threatened legal action.

During First Minister's Questions on Thursday, Nicola Sturgeon said she had "serious concerns" about Ryanair's decision to cancel Scottish flights.

CAA chief executive Andrew Haines said: "There are clear laws in place which are intended to assist passengers in the event of a cancellation, helping minimise both the frustration and inconvenience caused by circumstances completely out of their control.

"We have made this crystal clear to Ryanair, who are well aware of their legal obligations, which includes how and when they should reroute passengers, along with the level of information it provides its passengers."

Mr Haines said Ryanair's announcement on Wednesday that it was suspending 34 routes also failed to provide enough information to passengers.

All flights between London Stansted and Edinburgh and Glasgow have been cancelled until March, as well as those between Glasgow and Las Palmas, Gran Canaria; Edinburgh and Szczecin, Poland, and Edinburgh and Hamburg, Germany.

Ryanair has blamed its recent problems on a "roster failure" that resulted in too many holidays being booked between September and December.