(Adds quotes, background)
JERUSALEM, July 28 (Reuters) - Israeli Prime Minister Benjamin Netanyahu said on Monday his country must prepare for a long conflict in the Gaza Strip, squashing any hopes of a swift end to fighting that has already cost more than 1,000 lives.
In a televised address, a grim-faced Netanyahu said that any solution to the crisis would require the demilitarisation of the Palestinian territory, which is controlled by Hamas Islamists and their militant allies.
"We will not finish the mission, we will not finish the operation without neutralizing the tunnels, which have the sole purpose of destroying our citizens, killing our children," Netanyahu said, adding that it had been a "painful day".
Earlier, the Israeli army said Palestinian fighters had slipped across the border from the Gaza Strip, with media reporting casualties in an ensuing gunbattle. There were also reports of four Israeli deaths in a mortar attack, as an unofficial truce called for the Muslim Eid al-Fitr festival disintegrated.
"We need to be prepared for a protracted campaign. We will continue to act with force and discretion until our mission is accomplished," Netanyahu said.
Israel launched its Gaza offensive on July 8, saying its aim was to halt rocket attacks by Hamas and its allies. It later ordered a land invasion to find and destroy the warren of Hamas tunnels that crisscrosses the border area.
Some 1,054 Gazans, most of them civilians, have died in the three-week-old conflict. Israel has lost 43 soldiers to Gaza fighting and another three civilians have been killed by Palestinian shelling. (Reporting by Ari Rabinovitch; Writing by Crispian Balmer; Editing by Robin Pomeroy)
Our Standards: The Thomson Reuters Trust Principles.