By Saud Mehsud and Hafiz Wazir DERA ISMAIL KHAN/WANA, Pakistan (Reuters) - Pakistani Taliban fighters secretly buried their leader on Saturday after he was killed by a U.S. drone aircraft and quickly moved to replace him while vowing a wave of revenge suicide bombings. The Pakistani government denounced the killing of Hakimullah Mehsud as a U.S. bid to derail planned peace talks and summoned the U.S. ambassador to protest. Some lawmakers demanded the blocking of U.S. supply lines into Afghanistan in retaliation.