Hamas has executed four Palestinians on suspicion of “collaboration” with Israel since the beginning of the fighting in the Gaza Strip 10 days ago, the Palestinian daily Al-Quds reported Thursday.The paper quoted sources in the Gaza Strip as saying that another 13 Palestinians have been arrested by Hamas on suspicion of providing Israel with information about militiamen and homes of civilians.The sources said that Hamas’ armed wing, Ezaddin al-Qassam, has been using agents in civilian clothes to monitor the movement of suspected informants.Some of the detainees have been accused of “spreading panic and rumors among residents” by claiming that their homes would be targeted by Israel.