TEL AVIV ø Israel has installed a system meant to detect and alert authorities of a Palestinian missile attack.

Officials said the system has been installed in the southwestern city of Sderot, the target of Hamas gunners. About 500 Kassam-class short-range missiles have fallen in or near Sderot over the past three years.

The missile alert system has been commissioned by the military's Ground Forces Command and developed and produced by the state-owned Rafael, Israel Armament Development Authority. Officials said the system, provided to the military command last week, could detect a Kassam launch from the Gaza Strip and relay the time and place to the military and civilian authorities within two seconds.

"It can identify in a very short time where it [the missile] was launched and assess where it will fall and operate a warning system while the rocket is in the air, which is for about 20 seconds, depending on the range," Rafael chief executive officer Giora Shalgi said.

Called Ma'amin, or "Believer," the system would then relay an announcement to Sderot residents via the city's public address system. This would give residents about 15 seconds to find shelter before the missile lands in the city.

The average flight of the Kassam is about 20 seconds. More than 100 Kassam missiles, including 13 enhanced Nasser-3 missiles, landed around Sderot in 2004.

Officials acknowledged that the Ma'amin contains glitches. On Monday, the system did not alert Sderot residents of a Kassam missile attack from the neighboring Gaza Strip. A Kassam missile landed in a residential area of Sderot and nobody was seriously injured. The military said it had launched an investigation of the Ma'amin.

The failure of the system came one week after it was tested by the Ground Forces Command and deemed a success. The Ma'amin has been deemed as capable of detecting the position of a Kassam launch through the use of electro-optic sensors and software. The system, based on a Rafael platform to locate sniper fire, contains a thermal camera directed toward the northern Gaza town of Bet Hanoun, the launching pad of most Kassam strikes.

Rafael was said to have modified an existing anti-sniper system into a prototype for a missile alert platform within six weeks. Officials said the project came in wake of an emergency request fom the Defense Ministry in July.

Officials said the Rafael system could be expanded. to cover other areas of Israel. Shalgi said the enhancement would cost up to $10 million.

Israeli authorities expect missile attacks to intensify over the next few months as the government of Prime Minister Ariel Sharon prepares to withdraw from the Gaza Strip and northern West Bank. On Sunday, a leading Hamas operative, Khaled Abu Salmiya, linked to Kassam missile production and strikes against Sderot, was killed in an Israeli air attack in the Gaza Strip.

Officials said Abu Salmiya was responsible for the enhancement of the Kassam missile over the last three months.