A Scottish government decision to purchase the boats serving the Northern Isles ferry routes has put them further behind one of its own key green targets.
The SNP administration says the proportion of “green” ferries has fallen.
That is despite a commitment to ensure 30 per cent of state-owned ferries use environmentally-friendly technology by 2032.
Transport Secretary Michael Matheson has responded to questions from Jamie Halcro Johnston.
In a letter Mr Matheson stated the proportion of low emission ferries had dropped because of the purchase of the NorthLink boats.
He said the 2032 target was now “more stretching”.
Mr Halcro Johnston said: “The Scottish government really doesn’t have its problems to seek on ferries, and this is just the latest in a series of embarrassing revelations.
“Instead of greening Scotland’s ferry fleet, the Transport Secretary has confirmed that the Scottish government are actually going backwards on low emission ferries.”