Israel's Foreign Minister, Shimon Peres, has described Monday night's attack on Gaza City which killed 15 people - including nine children - as a mistake.

In a BBC interview, Mr Peres said the incident was regrettable and would be investigated.

I think all of us feel sorry for the loss of life of innocent people, particularly children

Shimon Peres

Earlier, the country's President, Moshe Katsav, said politicians in Israel must take responsibility for what he termed a mishap.

The attack targeted a leading member of the militant group Hamas, Sheikh Salah Shahada, who was among those killed when an F-16 jet dropped a one-tonne guided bomb on the apartment block where he was staying.

Shahada is blamed by Israeli security officials for dozens of suicide bombings during the Palestinian uprising.

About 140 people were injured in the strike

The raid, which Israel initially described as a success, has drawn widespread condemnation from other countries.

Palestinian officials accuse Israel of deliberately trying to sabotage efforts by militant groups to declare a ceasefire - something Israel has denied.

'Not aware'

"What happened is really regrettable. It wasn't done intentionally," said Israel's foreign minister.

"I think all of us feel sorry for the loss of life of innocent people, particularly children," Mr Peres said.

Those who decided to go ahead with the operation were "apparently not aware" that they were releasing a bomb onto a densely-populated area, otherwise they would not have done it, he said.

"We shall investigate very clearly what went wrong and draw all the conclusions," he said.

Prime Minister Ariel Sharon was quoted by the Israeli press as saying that if Israel had known there were so many civilians in the building, another way would have been found to kill the man who headed their country's wanted list.

Ephraim Sneh, a member of the Israeli security cabinet, told the BBC "maybe there was some miscalculation or mistake" in the operation.

Previous assassination attempts on Mr Shahada had been called off because of the risk to "innocent bystanders".

Palestinian anger

The attack came only hours after Hamas said the group was prepared to stop suicide bombings.

After the strike, Abdul Aziz al-Rantissi, a senior Hamas official, said: "I think the retaliation is coming and everything will be considered as a target for our assassins."

On Tuesday, about 300,000 Palestinians took to the streets for the funerals of the 15 people killed in the strike.

Only four of those killed were in the targeted house. The rest - including the children - were in neighbouring buildings.

Shahada: Israel's number one target in Gaza

A man held aloft the tiny body of a dead two-month-old baby wrapped in a flag, while masked men chanted: "Death to Israel! Death to America!"

Palestinian leader Yasser Arafat said: "This was an ugly crime, a massacre that no one who is sane or who has a conscience can imagine."

The United States, the United Nations and the European Union are among those who have strongly condemned the attack.

US President George W Bush described it as a "heavy-handed" action which "does not contribute to peace".

The Israeli military is to investigate the airstrike.

According to the BBC's Middle East correspondent, James Reynolds, this will focus on why an F-16 jet was allowed to drop a bomb on such a crowded residential area.