Spain's Prime Minister Pedro Sanchez. AFP
"The bases are not authorised, and of course neither is the use of Spanish airspace for actions related to the war in Iran," Margarita Robles told journalists, confirming a report by El País daily.
Spain's refusal to cooperate has "complicated" US military operations by forcing bombers to change their routes and logistics on their way to the Middle East, El Pais reported.
The transit or landing of planes is allowed only in case of an emergency, the newspaper said.
Spanish Prime Minister Pedro Sanchez has emerged as the highest-profile Western leader to consistently oppose the war, launched by US-Israeli strikes on February 28 and which has since engulfed the entire Middle East.
Last week, Sanchez warned that the Middle East war presented a "far worse" scenario than the invasion of Iraq in 2003.
"This is not the same scenario as the illegal war in Iraq. We are facing something far worse. Much worse. With a potential impact that is far broader and far deeper," he told parliament.
Spain's premier has refused Washington's requests to use Madrid's military bases against Iran, despite US President Donald Trump's threat to sever trade with Spain as a result.
Sanchez said the US invasion of Iraq in 2003 had failed to achieve its goals and instead made life worse for ordinary people, saying it led to a sharp increase in fuel and grocery prices, a migration crisis and jihadist attacks in Europe.
"Every bomb that falls in the Middle East eventually hits -- as we are already seeing -- the wallets of our families," Sanchez said.
His stance has infuriated Spain's traditional NATO ally, with US President Donald Trump threatening to cut trade ties in their latest policy clash.
Spain had already sparked Trump's anger by refusing to agree to raise NATO defence spending to five percent of member states' GDP as demanded by the US president.
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