The United States drafted a statement on Thursday that condemns as a "terrorist attack" an assault on a Jewish school in Israel, which it wants Libya and the other Security Council members to approve.
The draft was being discussed at an emergency UN Security Council session, called to debate an attack by a Palestinian gunman who opened fire at a Jewish religious school in Jerusalem. He killed at least eight people and wounded more.
"The members of the Security Council condemn in the strongest terms the terrorist attack that took place in Jerusalem March 6, 2008 which resulted in the death and injury of dozens of Israeli civilians," said the draft statement, obtained by Reuters.
Israel's enemy Libya is one of the 15 Security Council members. It was elected to the position last year, after the United States dropped its objections, and joined the council in January.
Several Western diplomats said Libya would find it difficult to accept the word "terrorist" in the statement, though it would probably accept another strong word. It was unclear if the Americans would be willing to compromise.
Libyan envoys were not immediately available for comment.
Over the weekend, Libya had objected to similar language in a council statement expressing concern about Israel's incursion into Gaza that killed more than 120 Palestinians. If Libya had not objected, it would have agreed to describe Palestinian rocket attacks against Israel as "terrorism", diplomats said.
Israel has said the rocket attacks were the reason for the incursion and its decision in January to close all of its border crossings into Gaza. The Palestinian militant group Hamas seized control of Gaza in June 2007.
In a statement to the council on Saturday, UN Secretary-General Ban Ki-moon described the Palestinian rocket attacks as "terrorism" but also called Israel's use of military force "disproportionate and excessive".
The council's statement on Gaza, approved early on Sunday, called on both sides to end the violence. It acknowledged Ban's statement but did not explicitly back it.