UNITED NATIONS, Aug 30 (Reuters) - Islamist militants surrounding 40 Filipino peacekeepers in Israeli-occupied Golan Heights have reinforced their siege with fighters who arrived in more than 20 vehicles, UN diplomatic sources told Reuters on Saturday."As we speak more rebels in more than 20 vehicles are approaching and reinforcing the siege around Position 68," a diplomat source said on condition of anonymity. The source added that the reinforcements began arriving at 11 p.m. local time.The United Nations says 32 other Philippine peacekeepers were rescued in a firefight earlier on Saturday. The militants surrounding the peacekeepers have been battling the Syrian army on the Golan Heights. Another 44 Fijian peacekeepers have been detained by militants nearby since Thursday.