Israeli warplanes early Sunday carried out an attack on the south of the Gaza Strip after rockets were fired at Israel, the army announced.

"During the night an Israeli plane hit an arms factory and a smuggling tunnel in the south of the Gaza Strip," the army said in a statement, adding: "This raid is in response to the rockets fired at Israel this weekend."

Two explosions were heard around Rafah but nobody was injured, Palestinian witnesses said.

Three rockets fired from the Gaza Strip had slammed into southern Israel on Saturday without causing casualties or damage, a police spokesman said.

Since the beginning of the year, Palestinian militants in Hamas-controlled Gaza have fired more than 50 rockets at southern Israel, army statistics show.

Hamas has maintained a tacit truce with Israel, but other armed groups regularly fire rockets across the border, usually sparking air strikes in response.