The return to Athens of 31 Greek activists who took part in the Gaza-bound aid flotilla was accompanied by a peaceful protest in central Athens against Israel’s deadly attack on a civilian ship convoy carrying aid to Gaza.

A Greek plane carrying 35 activists from the Gaza-bound aid flotilla landed at a military airport near Athens early Thursday.

The military aircraft brought 31 Greeks, 3 French and one US national released by Israeli authorities, the Air Force said.

They were welcomed at Elefsina airport by more than a hundred relatives and supporters, who cheered and shouted pro-Palestinian slogans. Deputy Foreign Minister Dimitris Droutsas and Greek lawmakers were also at the airport.

Greeks on the ships have said commandos assaulted and electrocuted them during the attack, even though they put up no resistance. They also accuse Israeli authorities of beating activists in custody, subjecting them to psychological torture and sleep deprivation.

Some 3,500 people have protested peacefully in central Athens against Israel’s deadly attack on a civilian ship convoy carrying aid to Gaza.

Shouting, “Whatever the Zionists do, we will sail to the port of Gaza,” and waving Palestinian flags, the protesters marched to Parliament late Thursday. They demanded that Greece presses Israel to return the six seized ships.

Earlier in the week Greece complained to Israel over the alleged mistreatment of Greek protesters detained after a deadly raid on the ships carrying aid to Gaza.

Senior foreign ministry official Ioannis Zeppos said Athens has demanded the “immediate release” of remaining protesters.