U.S. special Middle East envoy George Mitchell has embarked on his second trip to the region to further President Barack Obama's pledge to work for Arab-Israeli peace, the State Department said on Tuesday.

Mitchell was in London on Tuesday for talks with British Foreign Secretary David Miliband and would also visit the Turkish capital Ankara, the United Arab Emirates, Egypt, Israel and the West Bank before returning to Washington on March 4.

Miliband, who was to travel to Cairo later on Tuesday, told parliament in London he had met Mitchell "to discuss prospects for renewed talks on the future of the Middle East."

State Department spokesman Robert Wood said Mitchell would join U.S. Secretary of State Hillary Clinton in the Egyptian Red Sea resort of Sharm el-Sheikh on March 2 for a donors' conference to rebuild Gaza after Israel's invasion last December.

U.S. officials said on Monday the United States would pledge over $900 million, but none of those funds would go to the Islamist group Hamas which runs the Gaza Strip and is committed to the destruction of Israel.

Asked about Gaza aid on Tuesday, Clinton declined to provide details.

"We have made no decisions and we are working across the government to determine what our approach will be," she said.

Wood estimated the aid package -- a mix of new funding that still has to be agreed by Congress and already appropriated money -- would amount to hundreds of millions of dollars but he too provided no exact figure.