Grangemouth, Scotland's only oil refinery, has finally announced that it will cease all operations by the middle of next year, putting 400 jobs at risk.

Owner Petroineos, an integrated energy trading and refining company, announced last November that the plant would close, but gave no specific date.

At the time, union leaders had hoped it could remain open longer to find time for an alternative use for the site to be found.

Petroineos said the main reason for the closure was because it was now unable to economically compete with sites in Asia, Africa and the Middle East.

Grangemouth is the oldest of the UK's six refineries, although media reports said the facility is averaging daily losses of around $500,000.

In a statement, the company said the site would be converted into a terminal able to import petroleum-based products.

However, the workforce for such a facility would be around 100.

In the hours following the announcement, local Scottish news outlets reported that an international buyer could be make a serious offer to buy the refinery.

The outlets, citing Falkirk East Member of the Scottish Parliament, Michelle Thomson, said she had asked senior figures in the Scottish government for a meeting, to discuss finding a prospective buyer.