The Palestinian militant group Hamas appointed a replacement for Abdel Aziz Rantisi (search) on Sunday but declined to identify him after losing two leaders in less than a month to assassination by Israel.

Israel's Army Radio reported Mahmoud Zahar (search), Rantisi's second in command, had been chosen to oversee the group in Gaza. Hamas officials confirmed they had a new leader but, in a break with past policy, refused to give his name.

Hamas' Damascus-based leader Khaled Meshaal reportedly instructed the Gaza leadership to keep the identity of the new appointee secret.

Rantisi was killed Saturday by an Israeli missile strike on his car. He had been named Hamas (search) chief in the Gaza Strip after Israel killed Hamas founder Sheik Ahmed Yassin in an airstrike outside a Gaza City mosque.