Obama sounds a note of caution that there will be 'difficult times ahead'

The spirit and bravery of the Egypt's protesters who drove President Hosni Mubarak from power was hailed around the world but leaders simultaneously warned that the transition to a free society is far from over.

"The people of Egypt have spoken. Their voices have been heard and Egypt will never be the same," declared President Barack Obama in a statement from the White House in the US.

The president spoke of "the privilege of witnessing history taking place" but went on to caution that there is plenty of scope for "the Egyptian people's hunger for change" to be disappointed in the coming days and weeks: "This isn't the end of the Egyptian transition. This is the beginning. I'm sure there will be difficult times ahead."

The end of the Mubarak regime is already posing serious questions about the future of Arab-Israeli relationships as the fragile balance of power changes. In Gaza the resignation sparked hopes rose that the end of the Mubarak regime would mean Egypt would stop enforcing a border blockage on the territory imposed in 2007 when Hamas gained power. Ismail Haniyeh, the Hamas Prime Minister, said: "Egypt wrote today a new chapter in the history of the Arab nations and I can see the blockade on Gaza shaking right now."

Israel's government remained silent in the immediate aftermath of the Egyptian president's resignation but there was concern in the country about the implications. "We have a tough period ahead of us," Zvi Mazel, a former Israeli ambassador in Egypt, told Israel TV. "Iran and Turkey will consolidate positions against us. Forget about the former Egypt. Now it's a completely new reality, and it won't be easy."

Former Israeli Defence Minister Binyamin Ben-Eliezer, who was a long-time friend of Mubarak, said: "From this day on, I only have lots of questions about what will be the fate of the peace treaty between us and the Egyptians?"

Nerves in Tel Aviv were further tested by the claim by Mahmoud Ahmadinejad, the President of Iran, that changes in the Middle East would spell doom for Israel. He told a crowd in Tehran: "Despite all the [West's] complicated and satanic designs... a new Middle East is emerging without the Zionist regime and US interference, a place where the arrogant powers will have no place."

The United Arab Emirates and Jordan issued statements last saying they had confidence in Egypt's military rulers. In Tunisia, which is in transition after deposing Zine Abidine Ben Ali, the fall of Mr Mubarak was a step towards the "triumph of Arab causes".

David Cameron said: "Those who now run Egypt have a duty to reflect the wishes of the Egyptian people and, in particular, there really must be a move to civilian and democratic rule as part of this important transition to an open, democratic and free Egypt."