Friday was the first anniversary of Israel's withdrawal from Lebanon, and militant Palestinian Islamist groups Hamas and Islamic Jihad dedicated the attacks to their comrades Hezbollah, which led the Lebanese campaign to oust Israeli forces.

Israeli officials say the dead included Palestinian suicide bombers from three separate organisations - Fatah, Islamic Jihad and Hamas.

However, the Palestinians are blaming Israel for the Nablus blast, saying it was assassination.

We send our best regards to our brothers in Hezbollah

Hamas militant group

Israeli Prime Minister Ariel Sharon has said Israel would maintain a limted ceasefire for "a few more days" to give the Palestinians time to order a halt to violence.

The Palestinians have dismissed Mr Sharon's announcement of a ceasefire - under which Israeli troops are to fire only when their lives or those of other Israelis are at risk - as a ploy.

After the second bombing, the United States called on the Palestinian Authority to "make clear that terrorism is reprehensible".

Three explosions

The most deadly blast took place near the main bus station in the northern Israeli town of Hadera at about 1400 local time (1100GMT).

A car pulled up beside a public bus and exploded, killing two people in the car. As many as 67 people were injured, mostly with minor wounds or for shock, the Reuters news agency quoted police as saying.

Palestinians celebrated by burning a mock Israeli bus

"I heard an enormous explosion, and then I saw the burning car," a passer-by, Avi Yehezkel, told Israel TV.

Earlier, a lorry laden with explosives blew up near an Israeli military post at the Netzarim junction south of Gaza city.

The driver of the lorry was killed, but no-one else was hurt.

After nightfall, a Fatah member was killed and two others seriously wounded when a car carrying five men in the Balata refugee camp near Nablus exploded.

Earlier, Palestinian sources said the explosion was the result of a hand grenade going off accidentally.

But the official Palesitnian news agency later carried a statement by the Palestinian Authority accusing Israel of assassinating one of its members.

Lebanon connection

The Islamic militant group Hamas said it had carried out the Gaza Strip bombing to mark the first anniversary of Israel's withdrawal from Lebanon after a 22-year occupation.

Hamas identified the dead truck driver as 22-year-old university student Hussein Nasser and released video footage showing him holding a handgun and a mortar round.

"We send our best regards to our brothers in Hezbollah, and we renew our congratulations on the first anniversary of the liberation," Hamas said in a leaflet distributed in the Gaza Strip.

An Israeli army spokesman said the incident began when Israeli army vehicles blocked the Netzarim junction to Palestinian traffic to enable Israeli vehicles to pass.

"Suddenly the driver accelerated towards the post, the soldiers fired warning shots at him and the vehicle blew up," he said.

Israeli response

Israeli police inspect the remains of the Hadera bombing

Soon afterwards, Israeli forces entered Palestinian controlled areas of the Gaza Strip.

"Israeli tanks opened fire, lightly wounding three policemen, and advanced some 500 metres," police chief Saeb el Ajeez told the AFP news agency.

The Israeli army maintains it has been respecting a ceasefire in the territories since Tuesday evening.

In a separate development, the burnt body of an Israeli civilian, missing since Wednesday, was found near the autonomous Palestinian town of Tulkarm in the Gaza Strip, the Israeli army said.