Palestinian officials have accused the Israeli army of killing a five-year-old boy in the Gaza Strip.

They said that troops opened fire on a residential area of Khan Younis, killing Ayman Fares and wounding two relatives when they went to his rescue.

Whatever the circumstances, soldiers must not endanger the lives of civilians to protect their own B'Tselem human rights group

But the Israeli army denied any knowledge of the death, saying that its own men were attacked by gunmen in the area and had returned fire.

In a separate incident, an Israeli human rights group has strongly condemned the killing of a Palestinian teenager on Wednesday, after witnesses said he had been used by the Israeli army as a human shield.

Defending its troops' actions in Gaza, an army spokesman stressed that gunmen had opened fire from a built-up area, thus "putting innocents in danger".

Khan Yunis borders the heavily guarded Jewish settlement bloc of Gush Katif and exchanges of fire are common between them.

'Neither legal nor moral'

Leading Israeli human rights group B'Tselem has condemned the Israeli army for its use of Palestinians as "human shields" during raids on militants.

The army admits to the practice, but refers to it as the "neighbour procedure".

Nidal Abu Mohsen, 19, was shot dead when he tried to enter a house sheltering leading Hamas militant Nasser Jarrar in the West Bank village of Tubas on Wednesday.

The army said it was trying to take the Hamas leader alive

Palestinian sources said he had been forced to do so by Israeli soldiers besieging the house.

The Israeli army maintains that the dead teenager was trying to negotiate Jarrar's surrender when militants inside shot him dead, provoking a bloodbath in which the militant was also killed.

The same day, Hamas broke off talks with Yasser Arafat's officials on ending attacks on civilians inside Israel.

B'Tselem says the army has been using Palestinian civilians as shields against hostile gunfire since the current uprising started nearly two year ago.

"Using civilians as if they were bullet-proof vests and turning them into objects whose sole purpose is to protect soldiers is neither legal nor moral," it said.

"Whatever the circumstances, soldiers must not endanger the lives of civilians to protect their own."

'War footing'

The use of Palestinian "human shields" became a particular issue during Israel's sweeping military operations in April, when human rights organisations - including B'Tselem - petitioned the supreme court to order a stop to the practice.

The government did then outlaw it, but drew a distinction between "human shields" and what it called "neighbourhood procedure".

This involves deploying civilians to help soldiers enter Palestinian homes, or approach besieged militants to negotiate an end to a standoff.

B'Tselem said Wednesday's incident proves this procedure is just as dangerous as the one which was banned.

But many prominent Israelis do not agree.

A number of government ministers told Israeli media that the country was in a war situation, and sometimes the lives of Palestinian civilians had to be endangered to prevent attacks in Israel or to protect Israeli soldiers.

The controversy comes as the Israeli army says it killed two armed Palestinians on Thursday.

The two men were carrying a bomb and were shot dead as they crawled towards the fence around the Gaza Strip, the army said.