Palestinian mourners carry the body of the Islamic Jihad commander Tarek Abu Ghali, 28, during his funeral in the West Bank town of Jenin on Tuesday. Israeli forces killed Abu Ghali and another man during a military operation in the nearby town of Nablus earlier in the day. (Mohammed Ballas/Associated Press)Palestinian militants fired three homemade rockets from the Gaza Strip into Israel on Tuesday, threatening to unravel an Egyptian-brokered ceasefire between Islamic militant group Hamas and the Jewish state.

Two people were slightly injured in the barrage on the Israeli border town of Sderot, a community often targeted in rocket attacks.

Two Israeli women in the southern Israeli town of Sderot hug Tuesday as they stand at the entrance of a house after it was hit by a rocket fired by Palestinians from inside the Gaza Strip. (Tsafrir Abayov/Associated Press) One of the rockets struck an unoccupied home while two others fell inside the town, according to Israeli rescue service officials. The fourth fell in an open area.

Overnight, militants fired a mortar shell into the Negev desert, the first attack since the truce began six days ago.

The fringe militant group Islamic Jihad claimed responsibility for the rocket fire, which came shortly after an early-morning raid by Israeli forces in the West Bank city of Nablus that killed two Palestinians, including one of the group's senior commanders.

The Israeli military said the militant was preparing to attack Israel and that troops found explosive devices and munitions in his dormitory apartment at An-Najah University.

Bystander shot to death

A neighbour said a Palestinian bystander was also shot to death by troops when he opened the door of his apartment during the raid. The Israeli military spokesman's office said the man was a militant killed during a gun battle with troops.

In a statement released after the raid, Islamic Jihad said it would abide by the terms of the truce, but reserved the right to respond to what it said were Israeli violations of the pact.

Prime Minister Ehud Olmert's office called the rocket attacks a "blatant violation of the calm" but did not indicate whether Israel would respond.

In a statement, Hamas reiterated its commitment to the ceasefire saying: "We call on all factions to respect the agreement."

The attack prompted an urgent response from the so-called quartet of world powers — the United Nations, the United States, Russia and the European Union — meeting in Berlin to boost support for the Palestinian Authority police force.

The Berlin statement urged that "the calm be respected in full" and expressed the hope that it would endure, "and lead to improved security for Palestinians and Israelis alike, and a return to normal civilian life in Gaza."

The truce applies only to Gaza and calls for the cessation of Israeli incursions into the coastal territory and Hamas to stop militant rocket attacks into Israel.

Hamas still holds an Israeli soldier, Cpl. Gilad Shalit, who was captured in a raid in 2006.

Israeli newspaper Haaretz quoted an Israeli official as saying Tuesday that Egypt has assured the Israeli government that the Rafah border crossing between Egypt and Gaza would remain closed until a deal to release Shalit is reached.

With files from the Associated Press