The Israeli army launched new attacks on Sunday against targets of the Palestinian militant movement Hamas in the southern part of the Gaza Strip.

Palestinian and Israeli media have already reported new strikes in the central part of the enclave during the day, despite the ceasefire.

"In response to the flagrant violation of the ceasefire agreement that occurred this morning, the Israeli armed forces launched a series of strikes against Hamas terrorist targets in the southern Gaza Strip," the army said in a statement.

Humanitarian aid deliveries to the Gaza Strip have also been suspended"until further notice," an Israeli security official told AFP and AP.

The Times of Israel, citing a military source, added that one of the targets is reportedly a tunnel system that Hamas has used in the past to hold Israeli hostages.

The Hamas-run Gaza Civil Defense Agency said Sunday's Israeli airstrikes had killed at least 33 Palestinians so far.

The BBC reported that the attack in the town of Zawajda hit the entrance to a makeshift cafe, killing at least six people. Al Jazeera reported that strikes in the Nuseirat camp killed at least three people. Witnesses to Reuters also reported strikes near the towns of Khan Yunis and Deir al-Balah.

The Saudi-owned al-Hadath website reports that one of the victims of the attack west of the city of Deir al-Balah is Yahya al-Mabhouh - the commander of Hamas' elite military unit called Nukhba.

A senior Egyptian official involved in Gaza ceasefire negotiations told the AP, speaking anonymously, that"continuous" talks were underway to calm the situation.

The latest Israeli military strikes come after Prime Minister Benjamin Netanyahu ordered security forces to take"firm action" against Hamas targets, accusing the movement of gross violations of the ceasefire.

Israel said Palestinian militants violated the ceasefire on Sunday morning by firing an anti-tank missile at Israeli engineering vehicles and at Israeli forces around the southern Gaza Strip city of Rafah. Tel Aviv responded to the alleged ceasefire violations with airstrikes on the city of Rafah.

Hamas' armed wing insists the movement is abiding by the ceasefire and is not aware of any clashes."We reaffirm our full commitment to implementing everything we agreed upon, especially the ceasefire in all areas of the Gaza Strip," the Izz ad-Din al-Qassam Brigades said.