BARCELONA, Spain (AP) — A flotilla headed to Gaza that had departed Barcelona under much fanfare was forced back to port after a storm hit parts of Spain overnight.

The Global Sumud Flotilla, consisting of around 20 boats with participants from 44 countries, chose to return and delay its departure to “prioritize safety,” a statement said Monday.

Facing winds of over 56 kilometers per hour (35 miles per hour), some of the smaller boats taking part in the mission would have been at risk, it said.

The flotilla is the largest attempt yet to break the Israeli blockade of the Palestinian territory by sea.

It comes as Israel has stepped up its offensive on Gaza City, limiting the deliveries of food and basic supplies in the north of the Palestinian territory. Food experts warned earlier this month that the city was gripped by famine and that half a million people across the strip were facing catastrophic levels of hunger.

Thousands of pro-Palestinian supporters had gathered under a scorching sun on the docks of Barcelona's old port Sunday to cheer the mission as it took off.

Spain’s national weather agency AEMET had issued warnings of rainfall and strong storms for the region of Catalonia, as well as other parts of Spain.

It was unclear when the maritime convoy would depart Barcelona again. Other boats are expected to join from across the Mediterranean in the coming days, including from Tunis and Sicily.

Among the participants on board are Swedish climate activist Greta Thunberg and former Mayor of Barcelona Ada Colau. The flotilla also received support from Academy Award-winning actress Susan Sarandon and Liam Cunningham, known for his role in the HBO series “Game of Thrones.”

The Israeli military is likely to try and stop the boats from getting near Gaza, as they have done in the past.

The almost 23-month war has killed more than 63,000 people, with nearly 340 Palestinians dying of malnutrition, including 124 children, according to the Gaza Health Ministry.