Hamas is threatening to harm kidnapped Israeli soldier Gilad Shalit if Israel Defense Forces carry out a planned large-scale operation in the Gaza Strip, Israeli Army Radio reported Friday. The Saudi newspaper Al-Jarida reports that Hamas' Syrian-based leader Khaled Mashaal also threatened increased violence against Israel.According to the report, Hamas is threatening to carry out suicide bombings deep inside Israeli territory as well as kidnap additional Israeli troops. Hamas spokesman Abu Mujahed told Nazareth-based newspaper A-Sinara that if Israel were to invade Gaza, the group would begin rocket attacks on Israeli cities. The threat came as four Gaza Strip Palestinians were killed in an explosion during the funeral for an Islamic Jihad militant who died in an Israeli air strike, according to local medical officials and the police agency run by Hamas. The blast wounded 35 others, four critically, according to the emergency chief at Gaza City's Shifa Hospital, Bloomberg News reported. An Israel Defense Forces spokeswoman said the air strike followed the firing of a rocket barrage on Israel by Palestinian militants. The homemade Qassam rockets hit a house in the Israeli town of Sderot, injuring a woman, the IDF said.