The government of Algeria has suspended a co-operation treaty signed with Spain 20 years ago, accusing Madrid of reversing decades of neutrality on the Western Sahara conflict.
"Algeria has decided to immediately suspend the Treaty of Friendship, Good-Neighbourliness and Co-operation" signed with Madrid in 2002, the country's presidency said on Wednesday.
“Spanish authorities have engaged in a campaign to justify a stance they have adopted on Western Sahara, which contradicts Spain's legal, ethical and political obligations as an administering power in the region,” it said.
Spain in March publicly recognised Morocco's autonomy plan for the disputed territory to end a diplomatic spat with the kingdom, Algeria's arch-rival.
But Algiers said on Wednesday that move was in breach of Madrid's obligations towards the territory, a former Spanish colony largely controlled by Morocco.
In response, Algeria suspended the pact meant to promote dialogue and co-operation on political, economic, financial, education and defence issues.
Wednesday's move reflects Spain's complex challenge of balancing relations with Morocco and Algeria, which in August last year broke off diplomatic ties with Rabat over "hostile acts".
Spain expressed regret over Algeria's decision to suspend the treaty.
"The Spanish government regrets the Algerian decision to suspend the Treaty of Friendship, Good-Neighbourliness and Co-operation," said a diplomatic source.
Diplomatic dispute
Morocco controls 80 per cent of the Western Sahara.
The rest is held by the Algerian-backed Polisario movement, which fought a 15-year war with Morocco after Spanish forces withdrew in 1975 and has demanded a referendum on independence.
Morocco has offered limited autonomy but insists the phosphate and fisheries-rich territory must remain under its sovereignty.
Spain officially endorsed that position in March to help resolve a year-long diplomatic dispute after it had admitted the Polisario's leader, Brahim Ghali, to be treated for Covid-19.
Weeks after Mr Ghali's admission to hospital, more than 10,000 migrants crossed into Spain's tiny North African exclave of Ceuta, as Moroccan border forces looked the other way, in a move seen as a way to put pressure on Madrid.
In April Spanish Prime Minister Pedro Sanchez travelled to Morocco on an official visit to patch up ties, after his government backed Rabat's 2007 autonomy plan.
Algiers said on Wednesday that Madrid had thereby "given its full support to an illegal and illegitimate formula... advocated by the occupying power".
Spain's position is complicated because it depends partly on Algeria for natural gas.
That dependence that has become more acute because of Russia's invasion of Ukraine, but also because Algiers in October last year stopped pumping gas to Spain through a pipeline traversing Morocco.
