Tel Aviv/Gaza  - Israeli Foreign Minister Tzipi Livni said Monday that "progress" had been made in international efforts to reach a truce in Gaza, but "difficulties" remained.

Israel in the meantime kept up its offensive in Gaza, which entered its third week at the weekend, striking more targets from the air overnight, albeit a smaller number than in the earlier stages of the war.

A military spokesman in Tel Aviv said the Israeli Air Force attacked 12 targets throughout Gaza overnight, mostly houses of Hamas activists which he said were storing rockets and hiding tunnels. A few rocket-launching sites were also hit, as well as another smuggling tunnel near the border with Egypt.

"I don't accept that in a war against terror the UN decides when to stop," a defiant Livni told Israel Radio Monday morning.

She said that by launching the Gaza offensive, Israel had restored its "deterrence" against militant factions seeking to attack it, and had also hurt Hamas' ability to fire rockets against it.

The radical Islamic movement ruling Gaza nevertheless still launched some 20 rockets at southern Israel on Sunday, the military said.

Livni declined to say whether the offensive was in its final stages or when it would end.

She said any decision to end the offensive would be made "quietly" because Hamas leaders hiding underground in Gaza were listening to the radio's Arabic service.

The death toll stood at more than 900 Palestinians and 13 Israelis killed, as the offensive - aimed at curbing seven years of rocket and mortar attacks from Gaza against southern Israel - entered its 17th day Monday. (dpa)