Israeli troops clashed with Hamas militants inside the Gaza Strip today, killing eight Palestinians in fierce fighting that drew in Israeli aircraft, tanks and bulldozers.

Troops had ventured about half a mile into the coastal territory on a routine foray against militant positions used to launch rocket attacks on Israel when Israeli aircraft opened fire on a group of approaching gunmen, sparking a shoot-out on the ground.

A spokesman for Hamas said that its fighters launched the clash by opening fire at an Israeli undercover unit.

Witnesses reported a heavy exchange of fire as Israeli tanks and bulldozers moved in, and soldiers took positions on rooftops. Hamas and Islamic Jihad militants hit back with small arms fire, laid mines against the soldiers and shot mortars at the Erez passenger crossing between Israel and Gaza.

Two of the mortars landed on the Israeli side of the passage, which has been closed to most traffic since Hamas wrested control of Gaza last month, the army said. No one was injured, but the mortars set off a fire in a road at the crossing,

Hospital officials said six militants were killed, and Hamas said all belonged to its group. Among the dead was Mohammed Siam, 37, the Hamas field commander in central Gaza, Hamas TV said.

Israeli aircraft later dropped missiles at militant targets in the area, the army said. Hospital officials said two militants were killed and Hamas said both were its members.

The incident took place close to the Bureij refugee camp, in the central Gaza Strip, a site of frequent clashes between gunmen and the Israeli army.

Elsewhere, along Gaza’s northern border with Israel, Hamas officials said that some 15 tanks and three bulldozers had moved into Palestinian farms and were levelling the land. The army said it had no such vehicles in the area.

Meanwhile, in Gaza City, some 400 Fatah civil servants were prevented from entering their offices as part of the power struggle between the moderate Palestinian government in the West Bank and Gaza's new Hamas rulers. The territories have been functioning as separate entities since Hamas seized Gaza by force last month.

The Hamas-dictated work week in Gaza runs from Saturday to Wednesday, with Thursday and Friday assigned as the weekend. Salam Fayyad, the new Palestinian Prime Minister, recently announced the Palestinian work week would run from Sunday to Thursday, as it does in Israel.

Today, Hamas forces barred people from entering government offices, saying that they were closed because it was the official weekend. Most Palestinian civil servants are loyal to Fatah.

“We told them that the government in Ramallah announced new weekend days but they said the people in Ramallah are not the government,” said Imad, 40, who works at the public works ministry, and refused to give his last name for fear of Hamas retribution.

“We are not coming on Saturday because its the official weekend. This is the beginning of the battle against the coup government in Gaza,” he said.

Abu Dajana, a Hamas security officer, said the orders of the “legitimate government" in Gaza would be implemented.

Yesterday, Gaza government employees loyal to President Mahmoud Abbas collected their first full salaries in 15 months. Civil servants who sided with Hamas’s bloody takeover of Gaza were not paid.

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