(Adds quotes, background) LONDON, Jan 6 (Reuters) - British Prime Minister Gordon Brown warned on Tuesday that the Middle East faced its darkest moment but voiced optimism that a basis could be found for an immediate ceasefire in the Gaza Strip. The United Nations Security Council was due to meet later to discuss the crisis in Gaza, where Israeli forces have launched an offensive aimed at Islamist militants. "I am hopeful that the basis on which an immediate ceasefire can take place can be found," Brown told reporters. "It obviously depends on what we do on the crossings, what we do on the tunnels, what we do about the supply and trafficking in arms and what security we can give to both the Palestinian people and the Israeli people," he said. Asked about the situation in Gaza, where medical officials said Israeli tank shells killed more than 40 Palestinians on Tuesday at a U.N. school where civilians had taken shelter, Brown said: "This is a humanitarian crisis." "This is the darkest moment yet for the Middle East and it affects the whole of the world," he said. "We must work as hard as possible in the next few hours, and days if necessary, so there is an immediate and sustainable ceasefire." "I believe the basis of our proposals -- ones that we've circulated to other countries -- could achieve that ceasefire," he said, calling for an immediate ceasefire, an end to arms trafficking into Gaza and the opening up of the borders into Gaza under international supervision. "We've got discussions taking place with the Egyptians about what's necessary. There are proposals from Turkey," he said. "It's not possible to see a solution to this without there being some form of international engagement that will protect the security of the Israeli people and will create the viability that is necessary for open borders (for Gaza)," he said. Britain is a permanent member of the Security Council, which up to now has been unable to reach a common stance on the conflict. (Reporting by Adrian Croft; Editing by David Milliken)
Smoke rises as the sun sets in the northern Gaza Strip January 6, 2009. Israeli tank shells killed more than 40 Palestinians on Tuesday at a U.N. school where civilians had ...
