Israeli warplanes struck a number of sites in the southern Gaza Strip on Wednesday, causing some damage but no casualties, Palestinian residents and Hamas security officials said.

Residents said one air strike targeted tunnels which run under the Egyptian border at the town of Rafah that militants use to smuggle arms into the Hamas-run Gaza Strip. Another hit an already bombed security compound in the town of Khan Younis.

An Israeli army spokesman said the warplanes had hit seven tunnels and one other target in Gaza.

The strikes followed the firing of a mortar round into Israel by Gaza militants on Tuesday.

Since Israel's 22-day offensive in the Gaza Strip that ended last month in a ceasefire, Israeli leaders have said they would respond very harshly to any firing of rockets or mortar bombs into the Jewish state.

Officials from the Islamist Hamas group and Israel are trying to cement an Egyptian-brokered deal for an extended ceasefire, the opening of Gaza's border crossings and a prisoner swap between the two sides.

Israeli Prime Minister Ehud Olmert is due to convene his security cabinet later on Wednesday to discuss the outline of such a deal and possibly vote on it.