CAIRO — Iran and Egypt, two countries that long have been openly hostile to each other, made a surprise agreement Sunday to resume direct flights for the first time since radical clerics ousted Iran’s monarchy in 1979.

Civil aviation and tourism authorities meeting in Cairo signed an accord to begin 28 weekly flights between the two countries but did not specify a start date, media in both countries reported.

The pronouncement baffled observers. The two countries back opposing political camps in Iraq, Lebanon and the Palestinian territories, lack full diplomatic ties and continually snipe at each other. But Iran’s pro-government Fars news agency described the deal and a visit by an Iranian trade delegation to Cairo as “”a prelude to the resumption of ties between the two countries.””

The aviation accord comes as U.S.-backed peace talks between Israel and the Palestinians struggle for traction. Israel has refused to halt the expansion of settlements in the West Bank, and the Palestinians say negotiations cannot go on while construction continues.

The settlements are enormously unpopular in the Arab world, but there was no suggestion that Egypt was trying to gain leverage over Israelis or their American backers by making a deal at a time the West is trying to isolate Iran over its nuclear program.

“”This move has been long in coming,”” said Karim Sadjadpour, an Iran specialist at the Carnegie Endowment for International Peace, a Washington think tank. “”What’s remarkable isn’t the resumption of direct flights between Tehran and Cairo, the two largest cities in the Middle East, but the fact that it has taken over 30 years for it to happen.””

Iran appears to be seeking business opportunities to make up for economic troubles caused in part by international sanctions. On Sunday, Iranian aviation authorities announced a 30 percent increase in domestic air fares to make up for airline budget shortfalls. A day earlier Iranian officials announced a flurry of deals with Syria.

The Egyptian aviation accord coincided with the arrival of an Iranian delegation attending a World Health Organization conference in Cairo, and appeared to be part of a $1.37 billion deal recently announced between Egyptian tycoon Rami Lakah and Iran’s privately owned Kish Airlines, which now mostly flies Iranians between the Persian Gulf and Tehran.

Rapprochement between Egypt and Iran could change the diplomatic balance of the Middle East, but many hurdles remain. Tehran calls Egypt, which has a peace treaty with Israel, a U.S. lackey, while Cairo considers the Islamic Republic an exporter of extremist Islam and terrorism.

Egyptian officials have complained for years that Iran continues to publicly hail the assassin of Anwar Sadat, who signed Cairo’s peace deal with Israel. Egypt hosts the tomb of Shah Mohammed Reza Pahlavi and annually honors the late monarch, which ruffles Iran.