Rice and US Defence Secretary Robert Gates are meeting Egyptian President Hosni Mubarak and Arab ministers at the Red Sea resort of Sharm el-Sheikh.

The meeting comes after Washington confirmed plans for a massive arms deal for the region.

The tour is aimed at uniting US allies against Iran, Syria and Hezbollah.

Rice denied Iranian claims that US policies were spreading fear in the Middle East.

Iranian foreign ministry spokesman Mohammad Ali Hosseini had accused the US of tarnishing good relations between countries of the region.

The rare joint trip by US Secretary of State Condoleezza Rice and Defence Secretary Robert Gates is also aimed at encouraging their allies to help stabilise Iraq and bolster the US-backed Baghdad government.

"As security permits we hope more states would undertake more diplomatic missions to Iraq," Rice told journalists on her way to the Red Sea resort of Sharm el-Sheikh, appealing also for further Iraq debt forgiveness.

Arab diplomatic missions in Baghdad have scaled back their representation following a campaign of attacks and kidnappings.

The US officials' arrival was preceded by Washington's announcement on Monday of a multi-billion-dollar military aid bonanza for so-called moderate Arab states whose foreign ministers the US duo is due to meet.

"We will have a chance to talk about what initiatives we might undertake with our friends and allies in the security and political areas," Rice said. "We are very concerned to be able to provide for the security of our long-standing allies in the region.

"The United States revealed new military pacts worth 20 billion dollars (14.6 billion euros) for Saudi Arabia, 13 billion dollars for Egypt and 30 billion for Israel in a bid to counter Iran.

Iran's nuclear programme and influence among Shia Muslim militant groups have long been sources of US concern.

During a stop-over in Shannon, Ireland, Rice told reporters: "There isn't a doubt, I think, that Iran constitutes the single most important, single-country challenge to... US interests in the Middle East and to the kind of Middle East that we want to see."

The trip is the two officials' first joint tour of the region.

They will visit Egypt and Saudi Arabia together, and other countries separately.

Gates told reporters travelling with him that US officials wanted "to reassure all of the countries that the policies that (US President George W Bush) pursues in Iraq have had and will continue to have regional stability and security as a very high priority".