U.N. Secretary-General Kofi Annan has called for an immediate end to fighting between Israel and Lebanon's Hezbollah militia. 

In an address to the Security Council, Mr. Annan sharply criticized both sides in the current Middle East hostilities. He blamed Hezbollah for starting the crisis, saying the Iranian-backed militia's actions hold an entire nation hostage. At the same time, he condemned Israel's "excessive use of force," and called on both sides to provide for the safety of civilians caught in the crossfire.

"I repeat: hostilities must stop. But while they continue, it is imperative to establish safe corridors for humanitarian workers and relief supplies to reach the civilian population," stressed Kofi Annan.

Mr. Annan also called for an international conference on how to implement Security Council guidelines. But he admitted that a mission he sent to the region had concluded that in the short term, it will be difficult to negotiate a ceasefire.

"Let me be frank with the Council. The mission's assessment is that there are serious obstacles to reaching a ceasefire, or even to diminishing the violence quickly," he noted.

Israel's Ambassador Dan Gillerman suggested Thursday that there would be no early end to the hostilities. When asked by reporters outside the Security Council chamber how long the Israeli military actions would continue, he replied, "It will take as long as it takes."

The Security Council adjourned into a closed session immediately after hearing Mr. Annan's briefing. The Council has scheduled an open debate on the Middle East Friday.

Mr. Annan will discuss Middle East strategy over dinner Thursday evening with Secretary of State Condoleezza Rice.