An Israel Air Force aircraft bombed smuggling tunnels connecting Gaza with Egypt on Tuesday after a rocket launched from the Islamist Hamas-ruled Gaza Strip struck the southern port city of Ashkelon, Gaza residents and Hamas officials said.

One Israeli plane also fired a missile into a training position of the armed wing of Hamas in Abassan village east of Khan Younis in the southern Gaza Strip, Hamas and residents said.

There were no immediate reports of casualties in either of the attacks.

Residents of the southern Gaza town of Rafah said on Tuesday that they received telephone messages from the Israel Defense Forces warning them to leave their homes ahead of an impending air strike.

The town, on the frontier with Egypt, is a center for smuggling goods and weapons into the strip through tunnels under the border.

The recorded messages, in Arabic, said "people who work in tunnels, live near them or are giving logistical help to terrorists should evacuate the area immediately," residents said.

Prime Minister Ehud Olmert and Defense Minister Ehud Barak have instructed the IDF to launch reprisal attacks against Hamas targets following Tuesday morning's Grad rocket attack in Ashkelon.

Defense Minister Ehud Barak told an international conference in Herzliya on Tuesday evening that Israel was near its goal of restoring security to the Negev.

"We promised peace and safety to those living in Southern Israel and we will deliver," he said. "We now have to translate the military success to success on the ground - and that is not far from coming."

Olmert earlier vowed the "smallest provocation would bring the harshest reaction" until the rocket fire on Israel ceased.

"We prefer, usually, to do things rather than make declarations. And when we do things, they are heard from one end of the country to the other and from one end of Gaza to the other," he said during a tour in northern Israel.

Israel warned on Tuesday that Hamas was "playing with fire" shortly after Gaza militants fired a Grad rocket into the coastal city of Ashkelon.

Ashkelon Mayor Benny Vaknin said the rocket fired from Gaza struck an open area in the heart of a residential neighborhood.

There has been sporadic rocket and mortar shelling since the ceasefires were declared, as well as a roadside bomb blast that killed an Israeli soldier on a Gaza border patrol. Militants said they were responding to Israeli fire.

Israel has carried out air strikes since ending its 22-day operation the Gaza Strip but held back from a renewed ground offensive during a surge of violence. Three Palestinian civilians and a gunman have so far been killed.

The Grad that struck Ashkelon was the first such rocket to be fired at the city since a cease-fire ended Israel's offensive in Gaza last month.

Three people were treated for shock after the attack, which also caused damage to property.