US Defence Secretary Leon Panetta was headed to Cairo from Tel Aviv on Tuesday in an effort to defuse tensions between Egypt andIsrael that have mounted since the end of Hosni Mubarak's rule.
Before flying out after a one-day visit to Israel, Panetta said he will seek to encourage both sides to ease friction over the Sinai and will ask Egypt's military rulers to release an alleged Israeli spy.
Ilan Grapel, a US-Israeli dual national, is accused of spying for Israel and has been in custody since June 12 but Israeli officials say it is all a mistake.
Speaking to reporters in Tel Aviv on Monday, Panetta said he hoped Grapel would be released but did not say whether the accused would be freed during his visit to Cairo as reported by some media.
"There's really nothing I can say about the specifics of that," Panetta said.
"We have made our concerns known to the Egyptians about holding that individual," he said.
"We would hope that whether it happens with me, or whether it happens at some point in the future, that they do take steps to release that individual."
Grapel has been charged with being an agent of Israel's Mossad intelligence service and of sowing sectarian strife in Egypt during the uprising which ousted longtime US ally Mubarak in February after three decades in power.
Egypt said on Saturday it was considering releasing Grapel.
Relations between Egypt and Israel, which have been bound by a peace treaty since 1979, have entered a turbulent period since Mubarak's overthrow.
The end of the veteran strongman's rule has coincided with uprisings across the Arab world that could give greater voice to popular anger over Israel's treatment of the Palestinians.
Panetta expressed concern that Israel was "increasingly isolated" in the diplomatic arena and needed to work to shore up its relations in the region, particularly with Egypt and Turkey.
Speaking to reporters before his arrival in Tel Aviv on Monday, Panetta said Israel and Egypt needed to engage "directly" to defuse problems in the Sinai peninsula.
Israel has said an attack on its south in August was mounted from the Egyptian territory and has expressed concern that a "security vacuum" has developed there since Mubarak's fall.
In Cairo, Panetta is also due to discuss Egypt's plans for elections and a transition to a civilian-led government in talks with Egypt's military ruler Field Marshal Hussein Tantawi and Prime Minister Essam Sharaf.
The Pentagon chief planned to reassure Cairo of Washington's commitment to the two governments' longstanding security ties.
He will also "encourage the transitional government to take the necessary and irreversible steps to clear the way for democracy," said a senior defence official, who spoke on condition of anonymity.
Panetta met Egyptian Foreign Minister Muhammed Amr last week in Washington.
After a day of meetings in Cairo, Panetta is due to fly to Brussels to meet NATO defence ministers who plan to discuss the allied air campaign in Libya and the war effort in Afghanistan.