CAIRO – US Undersecretary of State for Political Affairs William Burns arrived on Monday to take stock of the situation in Egypt 10 days after the downfall of Hosni Mubarak, the US embassy in Cairo said.

Besides meeting leaders of Egypt's interim military-led administration, the Arabic-speaking veteran diplomat is to see representatives of civil society, the embassy said.

In announcing his visit last week, Secretary of State Hillary Clinton said the United States would offer Egypt -- already a big recipient of US aid -- some $150 million to help its political and economic transition.

Burns comes to Cairo as revolt in the Arab world -- inspired by the 18-day uprising against longtime president Mubarak and the earlier ouster of his Tunisian counterpart -- widens from the Gulf to the Maghreb.

He arrived shortly before British Prime Minister David Cameron flew into Cairo to become the first foreign leader to visit Egypt since Mubarak's resignation.

Speaking to reporters after a meeting with Arab League chief Amr Mussa, with whom he discussed unfolding developments in Egypt and the Middle East, Burns saluted Egyptians on the "historic transition to democracy".

Washington looked forward to listening to the priorities of the new government and it would encourage "concrete steps" towards real political change, he said.

"The United States looks forward to remaining a very strong partner of Egypt and the Egyptians," Burns added.

"This is a moment of extraordinary promise for Egypt and Egyptians," he said.

"It's a historic transition to democracy; it's a moment when voices and courage and sacrifice and the remarkable peaceful determination of Tahrir Square has been heard around the region and around the world."

He added: "We respect and admire what has been achieved -- but we know that the way ahead is not going to be easy."