BARCELONA — An aid flotilla bound for Gaza has been forced to turn back to shore, just hours after leaving Barcelona on Sunday.

The first convoy of the Global Sumud Flotilla, which is set to involve dozens of boats and participants from 44 countries, returned to port after facing winds of 56 kilometres per hour (35 miles per hour) overnight.

Around 20 boats had originally departed from Barcelona on Sunday, with thousands of pro-Palestinian supporters gathering at the docks of the city's old port to cheer them off.

They were due to be joined by other vessels from Mediterranean ports including Tunis in the coming days.

Organisers said the decision to return to Spain had been taken to "prioritise safety", adding that some of the smaller vessels could have been at risk in the adverse weather conditions.

Participants onboard the flotilla, which has called itself the largest to try to break the Israeli sea blockade of the Palestinian territory, include Swedish climate activist Greta Thunberg and Ada Colau, the former mayor of Barcelona.

It has also received support from Academy Award-winning actress Susan Sarandon and Game of Thrones actor Liam Cunningham.

Amid weather warnings for rainfall and strong storms in Spain, it remains unclear when the maritime convoy will be able to depart from Barcelona again.

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

The flotilla's first attempt to set sail for Gaza came after food experts warned last month that the territory was in the grips of famine, with half a million people across the enclave facing catastrophic levels of hunger.

Gaza's health ministry says 340 Palestinians in Gaza, including 124 children, have died of malnutrition so far.

In total, more than 63,000 Palestinians have been killed in Gaza in the almost 23-month war. - Euronews