The last car ferry connecting two points on the east coast of the Scottish mainland, will not be running this summer because of urgently needed harbour repairs.

It is unclear when the summer only service between Cromarty on the Black Isle and Nigg on the Easter Ross peninsula will resume.

Its medieval predecessor across the waters at the mouth of the Cromarty Firth used to carry King James IV of Scotland when on pilgrimage to the shrine of St Duthac at Tain.

But now the ferry Cromarty Queen can carry four cars and 50 passengers, between a slipway near the Nigg fabrication yard and one near Cromarty harbour.

However a major problem has emerged in Cromarty harbour. That's where the ferry berths overnight, alongside a concrete addition to he original 18th century harbour, built in the First World War. This berth has now been declared unsafe by the Cromarty Harbour Trust.

The Cromarty Queen was officially launched in 2011 by sailing enthusiast actress Penelope Keith who has a holiday house in a nearby village. The vessel was built specially for the route by Tom Henderson, managing director of the ferry company whose his family is local to the Black Isle.

It replaced an earlier vessel, the Cromarty Rose, which began operating more than 40 years ago to take workers over to the Nigg yard.

Mr Henderson said it had only been confirmed recently that they would be unable to use the ferry's normal berth, which left little time to come up with any alternative arrangements: "Other berthing options were offered, but they were either unsafe or impractical.

"We are absolutely gutted. We made a major investment in the ferry five years ago. She is currently sitting at Macduff but we now either have to look for alternative work or think about putting her on market. "

He said the business had been growing and last summer carried 17,000 vehicles and passengers

Local councillor David Alston is chairman of the Cromarty Harbour Trust. He said losing the ferry would be real blow to Cromarty and it underlined the pressing need to upgrade the harbour.

"We have had discussions with the Crown Estate to see if there is any prospect of investment from its coastal communities fund. We have also put a great deal of efforts in the past into lottery applications, without success. One of the big problems is that both the First World War addition and the original harbour which dates to 1786, form an A grade historically listed structure. That listing makes upgrading it far more challenging. We have now managed to get the business of the harbour into profit but clearly we urgently need major investment from the funding agencies."

The ferry had been running under contract to the Highland Council and a council spokeswoman said the authority regretted it would not operate this year.

"The council had a contract for a half-hourly ferry service between Cromarty and Nigg on seven days per week from June to September. The Cromarty Ferry Company indicated some weeks ago that they were unable to find suitable berthing for the vessel and might have to withdraw from the contract. Having been unable to find a solution, they gave notice on May 6 to terminate their contract.

Arrangements would be made for the road signs to the ferry to be covered and tenders would be invited for a reinstatement of the ferry from 2016, she said.