(Adds Miliband, details, quote from resolution, background)

UNITED NATIONS, Jan 8 (Reuters) - The U.N. Security Council will vote on Thursday on a resolution calling for an immediate ceasefire in Gaza that Arab diplomats hope will put an end to Israel's 13-day offensive against the Palestinian enclave.

"We have an agreed text," Saudi Arabia's Foreign Minister Saud Al-Faisal told reporters. "We are going to vote on it tonight on the Security Council. This is ... a historic event."

The resolution to be voted on "stresses the urgency of and calls for an immediate, durable and fully respected ceasefire, leading to the full withdrawal of Israeli forces from Gaza," according to a text obtained by Reuters.

Diplomats from all 15 council member states were discussing the draft behind closed doors ahead of the vote, which British Foreign Secretary David Miliband said he hoped would "send a very strong signal about the determination of the whole international community" to help the people Gaza and Israel.

The vote will end nearly a week of closed-door bickering over what -- if any -- text should be adopted by the council.

Arab countries, many facing strong anti-Israeli sentiment at home, had insisted the Security Council must issue a binding resolution that would force Israel to end its military campaign in the Gaza Strip immediately.

The United States, like Israel, was initially against the council passing any kind of statement or resolution on the conflict.

More than 750 Palestinians and 11 Israelis have been killed in the 13-day offensive aimed at halting rocket attacks from Hamas militants on southern Israel. (Reporting by Louis Charbonneau; Editing by John O'Callaghan)