The international community has reacted with shock over the Israeli assault on a UN observer post in Lebanon which killed four UN observers, and it has urged Israel to conduct an immediate investigation into the attack.

UN Secretary-General Kofi Annan said in a statement he was "shocked and deeply distressed by the apparently deliberate targeting by Israeli Defense Forces of a UN Observer post in southern Lebanon."

"This coordinated artillery and aerial attack on a long established and clearly marked UN post at Khiam occurred despite personal assurances given to me by (Israeli) Prime Minister Ehud Olmert that UN positions would be spared Israeli fire," Annan said.

He called on the government of Israel to conduct "a thorough inquiry" into this tragic incident and to inform the UN of its results "as soon as possible. "

China on Wednesday indicated it was "deeply shocked" by and "strongly condemned" the Israeli air raid and urged an immediate ceasefire.

One of the four UN observers killed in the attack was from China.

"China urges the concerned sides, especially Israel, to take tangible measures to ensure the security of UN peacekeepers," said Foreign Ministry spokesman Liu Jianchao.

Finland, which is holding the rotating presidency of the European Union, issued a statement on Wednesday condemning the Israeli attack and demanding a thorough investigation.

Finnish President Tarja Halonen said there was no justification for an attack on the UN post and called for a full investigation of the Tuesday incident, said a spokeswoman for the head of state.

Foreign ministers from China, Japan, South Korea and the 10-nation ASEAN bloc issued a statement on Wednesday condemning the attack.

"The ministers were deeply shocked and distressed by the apparently deliberate targeting by the Israeli Defence Forces of the United Nations Observer post in southern Lebanon," the statement said.

French President Jacques Chirac issued a condemnation of the attack and stressed the urgency of the need to stop the violence in the region.

This kind of attack on international peacekeepers should be condemned by everyone, he noted.

German Chancellor Angela Merkel's office expressed "deep regret" and hoped Israel would respect the special status and inviolability of UN delegations.

Lebanese Foreign Minister Fawzi Sallukh condemned the attack, saying it was "barbaric and premeditated".

The attack showed "once again that Israel makes no distinction between a woman, a child, a hospital or a UN post whose mission isto assure security and peace," he said in a statement.

Austrian Foreign Minister Ursula Plassnik informed her Israeli counterpart Tsipi Livni by telephone of her "indignation" at the incident, saying a strike on a UN post was "totally unacceptable."

In London, British Prime Minister Tony Blair's office said the incident was "deeply regrettable."

"We send our condolences to the families of those killed and the UN as a whole," a spokesman said.

Sweden was upset about Israel's attack, Foreign Office Minister Carin Jaemtina said on Wednesday.

He said the strikes must stop and all parties involved needed to show restraint.

Pakistan condemned the attack on the United Nations Observation post and expressed condolences to the families of the peacekeepers.

"We extend our heartfelt condolences to the families of the peacekeepers and their governments. We understand their anguish, as Pakistan is a leading contributor to the United Nations peacekeeping operations," the Pakistani foreign office said.

The Ministry of Foreign Affairs of Malaysia condemned the strike in a statement. It stressed that all parties in such a conflict must respect the neutrality of UN peacekeepers and ensure their safety.

Brazil's foreign ministry said in a statement that it was "deeply concerned" with the Israeli attack on the UN position.

"Brazil reiterated its strongest condemnation of the indiscriminate use of force, which inevitably results in civilian deaths," it said.

Danish Foreign Minister Per Stig Moeller on Wednesday called on Israel to launch a thorough investigation into the attack on the UN observers.