An explosion in the southern Gaza Strip killed four Palestinians on Saturday, said the local health ministry.
Medics at the scene blamed an Israeli tank shell for the explosion but an Israeli military spokesman denied the army's involvement: "We have no knowledge of any Israeli strike in the area," he said.
Local residents identified the victims as members of the Palestinian Islamic Jihad militant group. Islamic Jihad had not confirmed the men were members.
Protests in the Gaza Strip began on March 30 when Palestinians began demanding the right to return to their ancestral homes in what is now Israel.
Israeli troops have shot dead 31 Gaza Palestinians and wounded hundreds since the protests began, drawing international criticism of their lethal tactics.