A Chinese UN observer was among the four UN peacekeepers killed in an Israeli air strike on south Lebanon on Tuesday night.

The body of the Chinese victim, whose name is Du Zhaoyu, has been recovered, said sources of the United Nations Interim Force in Lebanon (UNIFIL). The UN observer from China was part of the U.N. peacekeeping mission in south Lebanon.

Milos Struger, spokesman of the UNIFIL, said earlier that an Israeli bomb directly hit the base of the United Nations Observer Group in the town of Khiam near the eastern end of the border with Israel.

By 03:10 am local time Wednesday, the UNIFIL have recovered three bodies of the victims from the rubble, including the Chinese observer.

The other three dead UN observers were from Finland, Austria and Canada, the UNIFIL sources confirmed.

Since Israel launched a massive military offensive against Lebanon and Hezbollah guerrillas on July 12, a Nigerian civilian employee working with UNIFIL and his wife, also a Nigerian, have been killed in the crossfire between Israeli forces and Hezbollah guerrillas in the southern port city of Tyre.

Five UNIFIL soldiers and one military observer have also been wounded, Struger said.

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

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

In Jerusalem, Israel expressed regret on Wednesday over the deaths of four U.N. observers in south Lebanon.

"Israel sincerely regrets the tragic death of the U.N. personnel in south Lebanon," said Israeli Foreign Ministry spokesman Mark Regev.

Editor: Yan