The mayor of a town on the front line of Israel's conflict with Palestinian militants resigned live on radio in protest at the government's failure to halt rocket fire from Hamas-run Gaza.

Militants in the Gaza Strip, seized by Hamas Islamists from their Fatah rivals in June, fire short-range rockets and mortars every day at towns in southern Israel. While few cause damage or injury, the rockets spark widespread panic among residents.

Asked whether he could continue as mayor of the southern Israeli town of Sderot, Eli Moyal told Israel Radio: "You know what? I cannot. And I hereby inform you that I am resigning as mayor of Sderot right now." Moyal said he hoped his "sacrifice" would increase pressure for tougher action.

The Jewish state yesterday mounted one of its biggest incursions into Gaza in recent months, sending dozens of tanks and armoured vehicles into the territory and killing at least five gunmen. Olmert said Israel would "not stop" until the threat of rocket fire was removed.

In retaliation, Islamic Jihad militants fired at least 14 rockets and mortars into Israel on Wednesday. They said Moyal's resignation was "a clear victory for the resistance". Moyal said almost 20 rockets had pounded Sderot by midday. "One day a rocket will fall on a kindergarten and will kill 20 children and then the entire government, and entire country, will rush into war, unprepared," he said. "I don't want to be there when this happens."

Israel, which withdrew troops and settlers from Gaza in 2005 but still controls its borders, regularly launches raids into the coastal strip to try to curb rocket fire but reiterated today a broader military offensive was not imminent.