BARCELONA, Spain (AP) — The European Union on Thursday urged Algeria to reverse its decision to suspend a two-decade-old friendship treaty with Spain.

Algeria ordered the treaty's suspension on Wednesday, the country's latest move to ratchet up pressure on Madrid after the Spanish government changed its long-standing policy regarding the contested territory of Western Sahara.

Algeria recalled its ambassador to Spain in March after the government in Madrid came out in support of Morocco’s pretensions to keep Western Sahara under its rule. Algeria supports the territory's independence movement from rival Morocco.

Spain was the former colonial power in Western Sahara until it was annexed by Morocco in 1975. Since then, neighbors Algeria and Morocco have been at odds over the fate of the Western Sahara, at one point fighting a desert war.

Algeria’s now openly hostile turn against a member of the European Union comes while Spain and the rest of the 27-nation bloc are hustling to find alternatives to Russian energy imports to protest Russia's war in Ukraine.

European Commission spokeswoman Nabila Massrali told reporters Thursday that the treaty decision is “deeply worrying, and we therefore call on the Algerian authorities to review their decision.

“Algeria is an important European Union partner in the Mediterranean (region), and a key actor for regional stability,” Massrali said. “We are evaluating the impact of the decision, and solutions must be found through dialogue and diplomatic means.

“We hope that Algeria will reverse its decision and work with Spain to overcome the current disagreement,” she said.

The practical impact of the diplomatic move is yet to be seen, although Algeria has reportedly ordered its national bank to stop facilitating payments with Spain, which could disrupt trade.

The Spanish government quickly moved to assuage fears that the supply of natural gas which Algeria pumps and ships across the Mediterranean Sea could be at risk. Spain relies on gas for one-third of its energy needs as it phases out coal and nuclear plants and boosts its significant solar and wind power sources.

Spanish Foreign Minister José Albares said that so far no Spanish companies working with Algeria have reported any “inconveniences.”

“What the gas companies are telling us is that the decision has not caused any difficulties,” he said.

Algeria’s Sonatrach was Spain’s leading supplier of natural gas last year, with more than 40% of its imports. Spain has since pivoted to the United States, which has become its leading supplier of gas in recent months, ahead of Algeria.

Laurence Thieux, a professor of international relations at Complutense University of Madrid, said Spain's government had miscalculated Algeria's willingness to retaliate but that she doubted the North African nation would threaten to turn off the spigot.

“I see it more as a political move. Algeria, like many counties in the region, is doing whatever it can to pressure Spain to push the pendulum back away from Morocco,” Thieux said.

Going as far as actually breaking its contracts to supply with Spain gas would likely be too risky for Algeria, she said. The country's fragile economy depends on its role as a energy provider yet needs foreign investment to boost its pumping capacity.

“It does not have much room for error,” Thieux said. “Since the invasion of Ukraine, Algeria has wanted to show that it can be a reliable gas supplier. It would hurt its image too much as a trustworthy partner" if it broke its contact with Spain.

Spain also imports large amounts of fertilizers from Algeria, while Spanish companies send primarily soy oil and meat products the other way.

While thousands of migrants from Africa depart Morocco for Spain each year, Algeria also plays an important role in controlling unauthorized migration from its coasts and in helping fight terrorism.

Spain, Morocco and Algeria have been caught in a three-way diplomatic tug-of-war over Western Sahara for the past year.

Trouble started when Spain allowed the leader of Western Sahara's separatist movement to enter Spain to receive treatment for COVID-19 in May 2020. Morocco responded by dropping its border controls around Spain's North Africa enclave of Ceuta, which was quickly overwhelmed by thousands of migrants.

Relations only normalized between Madrid and Rabat after Spanish Prime Minister Pedro Sánchez took the unpopular decision at home to back Morocco's plan to keep Western Sahara under its control as an autonomous area.

But that, in turn, has pushed Algiers away and brought Sánchez’s government intense criticism at home while Spain struggles with high energy prices driven by global inflation.

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Lorne Cook in Brussels, and Ciarán Giles in Madrid, contributed to this report.

Joseph Wilson, The Associated Press