The costs of two CalMac ferries being built at the Ferguson shipyard have risen again after regulators ordered safety changes.

Completing Glen Sannox and Glen Rosa will now cost at least an extra £24m, the yard’s boss has told MSPs.

The delivery date for the second ship has been pushed back by three months, to March 2025.

The passenger capacity of the ships may also be reduced from 1,000 to 852.

The two ships, which were meant to cost £97m, are now 3.5 times over budget and will be delivered six years late.

When government-owned ferries procurement agency CMAL placed the order with the Inverclyde shipyard nearly eight years ago, the two ferries were expected to cost £97m and were due for delivery in 2018.

The latest increases mean the ships will cost nearly £380m if written off government loans to the shipyard are included in the figures, as suggested by Audit Scotland.