The European commission has said the "simply unacceptable" imposition of high tariffs by the US on Spanish olives is already having a major effect on producers in southern Spain.

This week the US Department of Commerce announced that tariffs ranging from 7.52% to 27.02% would be needed to counteract Spanish olive prices, arguing that the fruits were being sold for 16.88% to 25.5% less than their real value.

On Wednesday, a commission spokesman told reporters in Brussels that the preliminary duties were already hitting producers in Andalusia, where olive production "has a very significant economic and social impact".

He said: "We are also well aware of the possible wider implications of this process and that is why the commission got involved so actively in these proceedings and will continue to do so."

The US has said its move covers Spanish olives of all colours, shapes, size, pitted and non-pitted, whole, sliced, minced, wedged or broken. Exports to the US were worth £50.3m in 2017.

Exports of black olives to the US fell 42.4% in the first quarter of this year compared with the same period in 2017, dropping from 6.9m kgs to 4m kgs, according to Spain's association of table olive producers and exporters (Asemesa).

"The decision by the US Department of Commerce to impose unreasonably high and prohibitive anti-subsidy and anti-dumping duties on Spanish olives is simply unacceptable," said the commission spokesman. "This is a protectionist measure targeting a high-quality and successful EU product popular with US consumers."

Spain's agriculture minister, Luis Planas, called the tariffs unjust and said he would raise the matter at a meeting of EU agriculture ministers in Luxembourg on Monday.

"It's an unfair measure because it has no economic or technical basis and it's worrying as it could call into question the rules governing international trade," Planas said on Wednesday.

He said the tariffs not only affected Spanish producers but could also challenge the common agricultural policy (CAP).

"A unilateral action of this nature cannot go unanswered," said Planas, adding that Spain's trade, industry and tourism minister would also be raising the issue with the EU trade commission.

Antonio de Mora, the secretary general of Asemesa, recently called on the EU commission to "defend the sector on the political stage as forcefully as it has defended steel and aluminium", saying CAP rules were at stake.

He added: "This precedent could mean that any agricultural sector in any country that competes with EU products that receive CAP assistance could ask its government to act like the US is."

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The issue of US tariffs has been a cause of concern in Brussels for months, with the commissioners for both trade and agriculture, Cecilia Malmström and Phil Hogan, working behind the scenes to protect the Spanish industry.

Brussels claims that Spain's support for producers is consistent with World Trade Organisation rules because they do not target a single industry or product.

The final US decision on the imposition of the tariffs is expected to be made on 24 July.