Spanish Foreign Minister José Manuel Albares demanded Saturday that Israel immediately release a Spanish-Swedish dual national detained after Israeli naval forces intercepted a humanitarian aid flotilla bound for Gaza in international waters, intensifying a diplomatic confrontation between Madrid and Tel Aviv that has been building since the war in Gaza began. The detained man, Saif Abukeshek, is being held for questioning along with Brazilian national Thiago Ávila at a detention facility in the Israeli port city of Ashkelon.

Both men have begun a hunger strike and reported being subjected to physical beatings while in custody, according to the Legal Center for Arab Minority Rights in Israel, or Adalah, an Israel-based legal advocacy group whose representatives visited the two activists at the detention site.

“Adalah maintains that the treatment of the two activists, including the use of isolation, prolonged blindfolding and physical beatings, constitutes a grave violation of international law,” the group said in a statement.

Albares confirmed he had raised the matter directly with his Israeli counterpart. “This is a case of illegal detention in international waters, outside the jurisdiction of Israeli authorities,” he said in an interview with Spanish public radio. “I have made this clear to my Israeli counterpart.”

Israel’s Foreign Ministry, in an online post, said Abukeshek and Ávila were being questioned for possible links to the armed group Hamas and that the two men had been granted consular visits. The ministry did not directly address the allegations of mistreatment raised by Adalah. Dozens of other activists aboard the flotilla were picked up by the Greek coast guard after the Israeli action and taken to the island of Crete.

The detentions have become the latest flashpoint in a relationship that has deteriorated sharply since the outbreak of the Gaza war. Spain formally recognized Palestinian statehood in 2024 and has been among the most persistent European voices criticizing the scale and conduct of Israel’s military campaign. The detention of a Spanish citizen appears to have pushed that criticism into a direct personal confrontation between the two countries’ leaders.

Speaking at a campaign event for his Socialist party ahead of regional elections in southern Spain on Friday, Prime Minister Pedro Sánchez took direct aim at Israeli Prime Minister Benjamin Netanyahu. “Now that Netanyahu has taken foreign citizens, including a Spanish national, and brought them to Israel, I have a few things to say to Prime Minister Netanyahu,” Sánchez said to applause.

He laid out three points. “First, Spain will always protect its citizens. Second, we will always uphold international law — and this is yet another violation of it,” Sánchez said. “And third, we demand the release of the Spanish citizen who has been illegally detained by the Netanyahu government.”