JERUSALEM, April 6: Israel's Prime Minister Benjamin Netanyahu charged today that a bomb explosion which killed a senior Islamic militant in the West Bank last week was new proof that Palestinian police were not seriously fighting terrorism.``As was proved in the recent case in which another bomb factory was discoverd in Ramallah, right under the noses of the Palestinian authority, there exists a widespread Hamas terrorist infrastructure in its territory against which the Palestinian authority is not acting systematically,'' Netanyahu said, according to official minutes of the meeting.``Due to the lack of such Palestinian activity, additional terrorist attacks are possible,'' he said.