Israeli tanks have shelled northern Gaza after officials warned they were turning part of the Strip into an exclusion zone to prevent extremists from launching rocket attacks from there. Earlier in the day Israeli warplanes bombed roads in northern Gaza and dropped leaflets in Arabic telling Palestinians the zone was now a “no go” area and anyone inside it was in danger. A map of the “exclusion zone” appears to show land where thousands of Palestinians live. Not so says the army, claiming the areas are abandoned former Jewish settlements.After forcing Jewish settlers to withdraw from Gaza, Israeli Prime Minister Ariel Sharon can ill afford to allow Palestinian extremists to use the abandoned land to strike Israel. Meanwhile, there has been more trouble on another of Israel’s volatile borders. Israeli planes have struck a Palestinian militant group’s training camp in southern Lebanon. It came just hours after a rocket strike on an Israeli town injured three people, raising border tension to its highest level in years.