A long-range Grad rocket from Gaza landed in the Israeli city of Ashkelon today as Hamas delegates met Egyptian officials in Cairo for talks aimed at securing a long-term truce with Israel.

The rocket was the first of its kind to be fired at the city of 122,000 since informal ceasefires were declared separately by Israel and Hamas two weeks ago at the end of Israel's three-week-long offensive in Gaza.

No one was injured in today's attack, police said.

Israel launched Operation Cast Lead on 27 December with the aim of stopping rockets being fired from Gaza on a near-daily basis at Israeli targets. Sporadic rocket and mortar fire from Gaza has continued, however, prompting tough warnings of reprisals from Israeli leaders.

More than a dozen rockets and mortar shells were fired into Israel on Sunday. The following day Israel fired a missile at a car in the town of Rafah, killing a Palestinian militant, and bombed the nearby Gaza-Egypt border, seeking to destroy tunnels that Hamas uses to smuggle in weapons and supplies.

The Israeli foreign minister, Tzipi Livni, pledged to keep hitting Hamas as long as it attacked Israel, and ruled out negotiations with the militant Islamic rulers of Gaza.

"Terror must be fought with force and lots of force. Therefore we will strike Hamas," she said at a security conference yesterday.

"If by ending the operation we have yet to achieve deterrence, we will continue until they get the message."

Continued violence could work against Livni's government in the 10 February general election and bolster the hardline opposition leader, Binyamin Netanyahu, who is seen as the frontrunner.

Ashkelon was hit by nearly 100 rockets during the Gaza fighting.