A leader of the exiled Guinean opposition said here today that Saturday's apparent overthrow of President Francisco Macias Nguema in Equaltorial Guinea, on the African west coast, was simply a ploy to attract vital foreign aid to the former Spanish colony.

Macias, whose 11-year totalitarian government reportedly drove half of the 400,000 population into exile, apparently was ousted Saturday in a confused coup organized by a revolutionary military council and led by Lt. Col. Teodo Boiang Nguema Mbasongo.

Macias is still at large. He and his personal bodyguards are holding out near his hometown, Spanish officials said today.

Spanish Foreign Ministry officials and the new Revolutionary Council had appealed to Macias to surrender and avoid bloodshed.

Antonio Ondo, secretary general of the opposition movement National Action for the Liberation of Equatorial Guinea, said the new leader is the nephew of Macias and had, in the recent past, acted as executioner for his uncle when, as army chief of staff, he ruthlessly repressed all dissent against the one-man government.

"What has happened is not a coup, not even a palace coup," said Antonio Ondo. "It is nothing more than a transfer of power; Teodoro was the regime's right-hand man. Nothing has changed." As secretary general of the opposition movement, Ondo claims to control 50,000 Guinean exiles, most of whom are based in neighboring Cameroon.

Teodoro Obiang Nguema has announced since the takeover that he will respect the U.N. Declaration of Human Rights and has declared an amnesty for political prisoners that could cover as many as 5,000 people.

Despite the opposition's misgivings, Spain has recognized the new leadership and sent a team of officials on a fact-finding tour of Equatorial Guinea.

According to the opposition here, the minimum conditions for the return of the exiles - 100,000 in Gabon, 30,000 in Cameroon, 30,000 in Nigeria and the remainder in Spain and other European countries - include the presence of observers representing the Organization of African Unity and the United Nations in Equatorial Guinea, and their supervision of free elections.

"Guinea is now ruined," Antonio Ondo said. "The country's economy is on its back and desperately needs foreign capital. Macias has acted through his nephew before anyone could act for him. He has retired himself."