Gaza/Tel Aviv  - Israel attacked smuggling tunnels along the Gaza Strip's southern border with Egypt early Thursday, responding to ongoing rocket and mortar fire from the coastal salient, the Israeli military said.

Two tunnels were destroyed in the overnight airstrike near Rafah, a military spokeswoman said.

She said the strike was a response to the firing of four rockets and one mortar shell by Palestinian militants into southern Israel the previous day.

Gaza militants have fired almost 170 rockets and mortar shells at southern Israeli towns and villages since January 18 when Israel ended a ferocious, 22-day offensive that aimed but has thus far failed to curb such attacks.

Since the offensive, Israel has responded to the ongoing fire at its southern region with airstrikes on tunnels and squads of militants returning from or about to fire the rockets.

The renewed cycle of violence comes as Israel and the de-facto Hamas government in Gaza are in intense, indirect negotiations on a durable truce that has thus far failed to come to fruition and on a prisoners exchange deal that would see the release of an Israeli soldier held captive in the strip since June 2005.

Israel Radio reported Thursday that Israel's negotiator on the prisoner exchange, Ofer Dekel, extended his current visit to Cairo.

It quoted government officials as saying there was "no breakthrough" but that the Israeli security cabinet could meet Saturday if progress was made. They said Israel would not open Gaza's border crossings - a Hamas condition for a truce - without the release of Corporal Gilad Shalit.

Outgoing Israeli Premier Ehud Olmert is making an intense, last-minute effort to free Shalit before prime minister-designate Benjamin Netanyahu completes his formation of a new government after February 10 elections.

Shalit's family has erected a protest tent outside the premier's office in Jerusalem, with the soldier's father, No'am, urging Hamas Wednesday to exploit the "window of opportunity" because "you will not get what you want" under the next, hardline Israeli government.

The radical Islamist Hamas movement ruling Gaza wants about 1,000 Palestinian prisoners in exchange for Shalit. (dpa)