GAZA CITY, Palestinian Territories (AFP) -- Gaza's nine-day-old ceasefire came under strain Sunday after the Israeli army said it launched air strikes in response to attacks it claimed were carried out by Hamas militants against its forces.
Hamas, however, maintained it was adhering to the truce, with one official accusing Israel of devising "pretexts" to resume its own attacks.
Later on Sunday, the military said in an online briefing that it launched strikes after attacks in Rafah, southern Gaza, and in the northern town of Beit Lahia, warning "there is a possibility of more strikes".
Gaza's civil defence agency, which operates under Hamas authority, said at least 13 people had been killed across the territory. The Israeli military said it was looking into the reports of casualties.
Israeli Prime Minister Benjamin Netanyahu earlier instructed security forces to take "strong action against terrorist targets in the Gaza Strip", his office said in a statement, accusing Hamas of "a ceasefire violation".
Defence Minister Israel Katz then warned that the group would "pay a heavy price for every shot and every breach of the ceasefire", adding Israel's response would "become increasingly severe".
The uneasy truce in the Palestinian territory, brokered by US President Donald Trump and taking effect on 10 October, brought to a halt more than two years of devastating war.
The deal established the outline for hostage and prisoner exchanges, and was proposed alongside an ambitious roadmap for Gaza's future but has immediately faced challenges in implementation.
"Earlier today, terrorists fired anti-tank missiles and opened fire on IDF (army) forces," in Rafah, the military said in a statement.
"The IDF responded with air strikes by fighter jets and artillery fire, targeting the Rafah area," the statement said.
Palestinian witnesses told AFP that clashes erupted in the southern city of Rafah in an area still held by Israel.
One witness, a 38-year-old man who asked not to be identified by name, said that Hamas had been fighting a local Palestinian gang known as Abu Shabab but the militants were "surprised by the presence of army tanks".
"The air force conducted two strikes from the air," he said.