At least 25 percent of Palestinians killed during Israel's onslaught on the Gaza Strip have been civilians, a United Nations agency says.

More than 390 Palestinians have been killed since the start of the Israeli campaign on Gaza, and some 1,900 others are reported wounded.

According to many Western media outlets, the ongoing strikes, which have now entered their fifth day, are the ugliest massacre Palestine has witnessed in decades.

"A minimum of 25 percent of all those killed are civilians and it may well be far higher," Christopher Gunness, a spoksman for the United Nations Relief and Works Agency for Palestine Refugees in the Near East, told AFP on Wednesday.

Israeli officials say the operation is aimed at taking out Hamas compounds throughout the coastal sliver.

In retaliation to the attacks on Gaza, Hamas has launched rocket strikes on Israel. Six Israelis have died since Saturday, while sixteen others have been reported wounded.

The UN figures come as Israel rejected an international proposal for a 48-hour humanitarian aid truce in Israeli offensive on Gaza.

"The cabinet decided to continue with the military operation," a senior Israeli official said Wednesday.

After the cabinet meeting, Israeli Prime Minister Ehud Olmert was quoted as saying that now is not the time to halt the ongoing offensive.

The Gaza Strip has been under an Israeli blockade since the democratically-elected Palestinian government of Hamas took control of the area in mid-June 2007.

MD/MMN