CAIRO, July 20 (Reuters) - At least 67 people were killed by Israeli fire while they waited for U.N. aid trucks in northern Gaza on Sunday, the territory's health ministry said, as Israel issued new evacuation orders for areas packed with displaced Gazans, some of whom began to leave.

The military told Palestinians to leave an area where many have sought refuge during the 21-month war and warned that it may expand operations.

The Israeli military has issued new evacuation warnings for central Gaza, an area where ground operations have been rare