The Crown Estate could soon be the subject of an enforcement notice over rubble and concrete that has been blighting a Highland seashore for 10 years.

Cabinet Secretary for Education, Michael Russell, the local SNP MSP, is backing the move, and is calling on the Crown Estate to show more responsibility for the local assets in its £7 billion portfolio.

But the Crown insists that although it owns the foreshore, the eyesore at Gallanach on the eastern shore of the Sound of Kerrera south of Oban, is not its responsibility.

Ten years ago a firm called Harper of Oban Engineering tried but failed to create a deep-water berth at Gallanach. The principal of the company, Donald Harper, had an accident and his company failed. A decade on, all that is left is piles of broken concrete and other building materials.

Ian Dougal, a development consultant who lives nearby, has been trying to get it cleaned up.

He said: "It is not only an unsightly mess and environmentally damaging in an area of natural beauty, it is dangerous. People walk across the foreshore and stand on the blocks, which can wobble. On one occasion it wobbled so much a man fell into the sea, was swept away and it took the coastguard an hour to get him.

"The Crown Estate needs to be part of the solution to clear it up and Mr Harper wishes to be part of the solution."

He thought they had found a way out. "Speculative building has all but ceased, but we thought a waterfront site might be the one thing that could spark interest," he said. "We got outline planning consent for four houses in November 2011 with the Crown Estate's support."

Crucially, the consents included the condition that nothing could happen until the foreshore was tidied up by whoever was building the houses.

Mr Dougal said: "Some months later the Crown Estate decided it was in its best interests to sell the foreshore." He said his consultancy was given the opportunity to buy it, but there was the impediment of the Crown Estate already having leased the foreshore to another company in a long-term deal.

He added: "The main stumbling block is we need the current lease to be terminated. But absolutely nothing has happened."

Mr Russell said: "This is a classic example of the problem of dealing with the Crown Estate. I encourage the council to take enforcement action. They have the power to do that."

Louise Glen-Lee, Argyll and Bute's lead councillor for the Oban, Lorn and Isles area committee said: "If enforcement action needs to be taken it will be, whether against the Crown Estate or anybody else. Things can't be left the way they are.

"I don't know if a local authority has ever taken enforcement action against the Crown Estate. But what needs to happen will happen. Nobody is beyond the law."

Alan Laidlaw, portfolio manager, rural and coastal, for the Crown Estate, said: "Primary responsibility for the present situation and for tidying the site lies with the person responsible for dumping the material. The Crown Estate has been working for a considerable time with those interested in the site with the aim to bring it back into productive use and to improve the gateway into the Sound of Kerrera.

"To that end, we are in discussions with interested parties and hopeful a conclusion will be reached in the near future."