Rebels say they shot down a U.S. locust-spraying plane in the belief it was a Moroccan military transport and apologized for the attack, which killed the plane's five American crewmen.

The Polisario rebel movement said Sunday it would retrieve the five bodies from the desert and return them to their families in the United States. It made no mention of compensation, and it wasn't known how long the recovery would take.The DC-7 was shot down Thursday in one of the most desolate parts of the Sahara Desert. There is no regular human settlement for more than 50 miles in any direction, and nothing grows in the wilderness of rock and sand.

A second DC-7 was also hit but managed to make it to an airfield 400 miles away and made an emergency landing with its five crew members safe.

A statement issued by the Marxist-led Polisario group said the attack, in the no man's land between Morocco's defensive wall and the Mauritanian border, was "neither premeditated nor intentional." It expressed "deep sorrow."

The statement, telexed from Polisario headquarters in Algiers to The Associated Press in New York and distributed locally, said the planes were mistaken for Moroccan military C-130s.

It said Polisario would return the five bodies to their families without delay.

It ascribed the incident to the spirit of Polisario's desert patrols, who it said were "daily attacked by Moroccan aircraft."

There was no immediate reaction to the statement from Moroccan authorities.

Morocco has insisted that the incident happened over Mauritanian territory. Following vigorous Mauritanian denials, however, a Moroccan government statement late Saturday acknowledged the planes were attacked over the 40-mile-wide no man's land between the defense wall and the border.

The planes were chartered by the U.S. Agency for International Development and were flying from Dakar, Senegal, to Agadir to take part in the campaign against the growing plague of locusts along the fringes of the Sahara.

Polisario has been fighting Moroccan forces for control of the Western Sahara since the Spanish army withdrew from the former Spanish colony in 1975. The United Nations is trying to organize a referendum among 80,000 inhabitants, but Polisario insists on a prior withdrawal of Moroccan troops and administrators.

The two sides also disagree about who should be allowed to vote.