Israel's deputy defence minister has called for a new invasion of Gaza and the capture of land close to the border, despite growing domestic and international concern about the conduct of the previous war.

"We need to conquer the areas from which mortar shells are being fired," Matan Vilnai told an Israeli conference on the Gaza war last night. "The mortar shell is the main threat," he said. Most were launched from within four miles (6km) of the border. "We just need to be there," he said.

His comments reflected a wider Israeli frustration with the results of the devastating three-week war. Israeli forces destroyed thousands of homes and buildings and killed more than 1,400 Palestinians but failed to achieve their main goal: to halt the rockets and mortars which are still being fired into southern Israel.

Binyamin Netanyahu, who is expected to become the prime minister of a new, rightwing Israeli government within days, has decided that "toppling the Hamas government in the Gaza Strip" will be a strategic goal of his government.

The latest criticism of Israeli military conduct in Gaza comes in the wake of fresh testimony last week from Israeli soldiers who gave accounts of how Palestinian civilians were killed and their homes ransacked. Themilitary said it would investigate the claims.

This week Richard Falk, the United Nations special rapporteur on human rights in the occupied Palestinian territories, is due to report to the UN human rights council. An advance copy of his report is highly critical of the war, saying Israel's "recourse to force was not legally justified given the circumstances and diplomatic alternatives available, and was potentially, a crime against peace". He calls for an expert inquiry into war crimes allegations against Israel.