BAGHDAD, Iraq, Jan. 13 (AP) - More than 70 American activists arrived on two separate flights Saturday to deliver medicine, books and school supplies as part of the growing international challenge to the 10-year-old international embargo against the Arab nation.

The Americans, mostly members of religious and humanitarian organizations, make up one of the largest U.S. contingents to visit Iraq since the 1991 Gulf War. A pair of Royal Jordanian flights ferried them from Amman, capital of neighboring Jordan, adding to the dozens of planes that have touched down at Saddam International Airport following a decade of U.N. sanctions that had effectively banned air travel.

``We're probably the first Americans who have flown over Iraq for a long time who haven't brought bombs,'' said organizer James Jennings, head of Atlanta-based Conscience International.

``All these people have come together to show that there are many thousands of Americans who are concerned about the devastating effects of these sanctions,'' he added.

The visiting Americans did not request U.S. government permission for their trip. However, they did not technically violate the sanctions placed on Iraq after its 1990 invasion of Kuwait. Jordan, which owns the airline, received advance approval for the first flight from the U.N. sanctions committee, officials said. It was not immediately known whether the second flight was also approved, but Jordan routinely applies and receives approval for its Baghdad flights.

``Down USA'' is painted in large black letters on the sidewalk at the entrance to the airport and similar handwritten signs are posted throughout the massive terminal building.

However, a delegation of more than 100 Iraqis led by Health Minister Omed Medhat Mubarak warmly greeted Jennings' group on the tarmac on a cold, foggy day.

``We think this is a very important event, because it has been the Americans who have imposed the embargo for more than 10 years,'' said Mubarak.

The second group of Americans, headed by former Attorney General Ramsey Clark, arrived Saturday night.

``There's been great progress made in ending the sanctions,'' Clark said as he stepped off the plane. ``What I hope and believe ... is that the rest of the nations of the world will simply refuse to participate in a criminal conspiracy against the people of Iraq.''

Several Palestinians wounded in clashes with Israeli forces also arrived on the flight, and will receive medical treatment in Iraq.

The Americans brought a total of $250,000 worth of medicine, eyeglasses, school supplies and medical books for the Iraqis.

U.S. activists have periodically brought humanitarian aid before, but they have usually traveled overland from Jordan. In 1998, an AmeriCares volunteer group flew into Baghdad with humanitarian supplies after first receiving permission from the U.S. government.

The de facto air embargo began to weaken in September, when French and Russian planes flew to Baghdad without the approval of the U.N. sanctions committee. Since then dozens of flights from European and Middle Eastern countries have arrived in the Iraqi capital carrying aid, activists and businesspeople.

Most of the flights have received approval from the sanctions committee, skirting the sanctions issue by including humanitarian aid, which is permitted.

At the United Nations on Friday, a U.S. official said that Washington allowed the Jordanian flight to be approved, though it was viewed as a ``propaganda tool for Iraqi President Saddam Hussein.''

``It's well documented that there is plenty of food and medicine to go around in Iraq. But Hussein chooses not to distribute it,'' said Mary Ellen Glynn, spokeswoman at the U.S. mission.

In a similar statement on Saturday, P.J. Crowley, spokesman for the National Security Council, said in Washington that a U.N. oil-for-food program in force since 1996 meant that Iraq had enough food and medicine.

``The oil-for-food program, which we have long supported, remains the best path to ensure that humanitarian assistance gets to the Iraqi people without directly or indirectly supporting Saddam's regime,'' said Crowley.

The sanctions, which Iraq blames for more than 1 million deaths since 1990, can be lifted only when the United Nations can verify that the country's programs for weapons of mass destruction have been dismantled. Iraq claims it has done so, but the United States and others say it is still withholding both material and documents.