(Decanter) - A shortage of grapes in the Spanish wine regions of Priorat and Mallorca has led to a surge in prices and is causing concern among some producers.

Rising demand for grapes in Priorat - already the source of some of Spain's most expensive wines - has caused a spike in grape prices, said Valenti Llagostera, from Mas Doix, one of the area's leading red wine producers.

Producers were paying 3 euros ($3.1) per kilo, and in some cases as much as 6 euros per kilo, for red grape varieties, he said.

A study from Catalonia’s Technological Wine Park shows that in 2013, the average price for the Carignan grapes was 1.79 euros per kilo with Grenache selling at 1.4 euros per kilo.

It remains unclear what the situation will mean for retail wine prices for consumers.

'There is a shortage of grapes,' Llagostera told Decanter.com on the sidelines of the Decanter Mediterranean Fine Wine Encounter in London last weekend.

'We produce 30,000 bottles of our Les Crestes wine, for example, and we would like to produce 60,000 bottles, but the shortage means this is not possible.'

Priorat’s regulatory council declined to comment on the issue. A spokesperson said official data on the average prices per kilo was not yet available.

Similar concerns over grape shortages have been voiced from producers on the island of Mallorca.