More than 250 cultural figures from across Spain, including the film director Pedro Almodóvar and the Money Heist actor Alba Flores, have signed a letter calling on the Spanish government to urgently impose a “comprehensive arms embargo” on Israel.

The letter, made public this week on social media and addressed to the prime minister, Pedro Sánchez, calls on Spain to formally ban the export and import of military material to and from Israel and says: “History will judge us by our actions at critical moments like this. Let us put an end to this horror.”

In the year since the Hamas-led attack on Israel on 7 October 2023 in which more than 1,200 people were killed, Sánchez has emerged as one of the EU’s most outspoken critics of Israel’s response, which has so far killed more than 42,000 people, many of them civilians.

This month Sánchez condemned attacks by Israel’s armed forces against the UN peacekeeping force in Lebanon and said Spain had halted the issuing of licences to companies for the sale of weapons to Israel in October last year. He urged the international community to do the same to prevent further escalation of violence in the region.

Research by the Barcelona-based Centre Delàs, which focuses on issues related to disarmament and peace, has suggested a more nuanced picture, however. In February the centre revealed on the news site Eldiario.es that ammunition worth €987,000 had been exported to Israel from Spain in late 2023.

The Spanish secretary of state for trade said the exports were related to licences issued before 7 October and described the materiel as “medium-calibre ammunition without explosives”, in comments made to Eldiario.es. The exports had been used in “testing or demonstrations” rather than in conflict, it was said.

On Wednesday the ministry responsible for trade did not reply to a request for comment from the Guardian.

The letter to Sánchez argues that the provision of arms and continued purchase of military material from Israel is financing a “genocide against Palestinian population”, leading to a greater loss of lives and more civilian suffering.

“We call on you to take urgent action to impose a comprehensive arms embargo on Israel,” the letter states, describing such a measure as a powerful tool that has proven effective in maintaining peace. “We know that it is in your hands. It is not only a moral imperative but also an obligation under international law.”

It calls on Sánchez’s government – which in May was among the nations that recognised Palestinian statehood – to do more to protect the rights of people in Palestine and Lebanon. “Internationally, Spain has stood out as a country that has positioned itself in favour of peace and the Palestinian people,” the letter states. “But this is not enough. As long as Spain continues to have military relations with Israel, it will continue to be complicit in this massacre.”

Earlier this month the French president, Emmanuel Macron, called for countries to stop supplying arms to Israel, in comments seen as largely aimed at the US.

It prompted a swift rebuke from Israel’s prime minister, Benjamin Netanyahu. “As Israel fights the forces of barbarism led by Iran, all civilised countries should be standing firmly by Israel’s side,” Netanyahu said in a video statement. “Yet President Macron and other western leaders are now calling for arms embargos against Israel. Shame on them.”

The UN’s special coordinator for the Middle East peace process, Tor Wennesland, said at the weekend that nowhere was safe in Gaza. “The nightmare in Gaza is intensifying,” he said. Horrifying scenes are unfolding in the northern strip amidst relentless Israeli strikes and an ever-worsening humanitarian crisis.”