Israeli Prime Minister Ehud Olmert has threatened a "disproportionate" reaction to Hamas rocket fire aimed at southern Israel.

At least two rockets launched from Gaza struck the south region of Israel on Sunday morning, attacks that came during a ceasefire that ended a 22-day Israeli offensive on militants. Two Israeli soldiers and one Israeli civilian were injured in the rocket attacks.

"The cabinet's position from the outset was that if there is rocket fire at southerners, there will be a response that will essentially be disproportionate," Olmert said at his weekly cabinet meeting.

Late Sunday, Palestinians said Israeli aircraft fired on an empty police station in central Gaza but no one was hurt. Also, Palestinians said residents near the Egypt-Gaza border received calls after nightfall from the Israeli military advising them to leave ahead of Israeli attacks on smuggling tunnels. The military had no immediate comment.

Since Israel declared the Jan. 18 truce, Hamas has continued sporadic attacks. In the most serious incident, an Israeli soldier was killed and three fellow soldiers were wounded in a blast near the Kissufim border crossing last Tuesday. Israel responded with air raids and a brief ground incursion by soldiers and tanks.

"We won't return to the rules of the game that terror groups have tried to dictate and we won't be dragged into a never-ending shooting war," the prime minister told cabinet ministers.

Israel has been chastised internationally for what critics say was its use of disproportionate force during its offensive.

The Israeli military carried out the aerial and ground assault, it said, to end rocket fire on southern Israel from Hamas-ruled Gaza.

The three-week campaign killed 1,285 Palestinians, mostly civilians, according to the Palestinian Centre for Human Rights.

Thirteen Israelis, including three civilians, were also killed during the fighting, according to the government.