The Israeli army has told Palestinians to leave areas in southern Gaza ahead of what it said would be "intense fighting” with Hamas, a sign it plans to extend ground operations to pressure the militant group into releasing hostages still held captive.

The notification on Monday covered Rafah, a city near the border with Egypt, as well as surrounding areas. People were told to move to Al Mawasi, an area near the coast. Two Israeli military officials, speaking on condition of anonymity, said a ground operation would follow against targets related to Hamas and other fighters in the area. The army had previously said it was widening a security corridor along the Gaza-Egypt border.

Israel halted aid flows into Gaza and resumed air strikes and ground operations in the enclave after a six-week ceasefire expired March 2. Israel says it won’t relent until Hamas, designated a terrorist group by the U.S. and many other countries, is no longer in power nor armed. It also aims to free 59 hostages still held in Gaza, as many as 24 of whom are believed to be still alive. Prime Minister Benjamin Netanyahu has said he will use a mix of military force and diplomacy to recover them.