Fears that cups of coffee could become more expensive have grown after bean prices soared to a seven-year high.

The price of robusta beans jumped three per cent to $1,668 (£882) a tonne for delivery in September and two per cent to $1,560 (£825) for November.

The prices came amid dwindling global supplies and lower exports from Vietnam, the world's biggest producer, where heavy rain disrupted operations.

There is also the threat of falling Indian production next year because of crop damage by rain and pests.

The price of robusta coffee lifted around 50 per cent in the last year. There has been a smaller increase in the cost of the milder and more aromatic arabica due to a drought in Brazil. Arabica accounts for 65 per cent of global production while the more caffeine-rich robusta make up 35 per cent.

The rises could lead to more expensive coffee in supermarkets and shops, according to the International Coffee Organisation (ICO) in London.

ICO head of operations Pablo Dubois said: "It will eventually put up the price a little but not by much."

He said raw material only accounted for 20 per cent of the price in supermarkets and five per cent in coffee shops - other factors such as packaging and wages had more of a bearing on retail prices.

Global demand for robusta outstripped supply after production fell from 114 million bags to 106.32 million bags.

Mr Dubois said robusta coffee would continue to rise for weeks although it could fall once the harvest of next year's crop starts in October.