Hundreds of Cubans wounded fighting in Ethiopia's Ogaden Province early this year were sent to the Soviet Crimea for medical treatment and convalescence, according to French official sources.

The sources said that there is good reason to believe that the wounded Cubans were sent to the Soviet Union rather than home because the arrival in Cuba of large numbers of wounded men was seen as a potential public morale problem.

Cuban forces in Africa are estimated at 40,000, almost a third of the Cuban Army's regular strength. Western sources say the Cubans have had to call up large numbers of reservists ranging up to age 40 to fill the gaps created by the number of troops shipped to Africa.

The French report underlines how heavy the fighting was in the Ogaden, the southeastern desert province that Somalia tried to wrest from Ethiopia last fall.

It also shows how closely linked Soviet and Cuban efforts in Africa have been.

The Crimea, a peninsula on the Black Sea, has traditionally been a rest and recreational area in Russia. The Soviets have converted the dozens of pre-revolutionary aristocrats palaces into clinics and rest homes for Soviet workers.

State Department estimates placed about 15,000 Cuban military personnel in Ethiopia in April. It is thought that more than half of the Cubans were sent to the Ogaden, where they turned the tide against the Somali Army, which had been trained previously by the Soviets. The report that hundreds of Cubans were wounded also implies that there must have been a large number of Cubans killed.

[U.S. officials have indicated that Cuban casualties in Ethiopia and earlier in Angola probably numbered in the hundreds and were certainly no more than one or two thousand men.]

A well-informed African diplomatic source here said that, as of May 15, the Western Somali Liberation Front, the screen organization behind which the Somali Army fought in the Ogaden, was holding prisoner 36 Cubans, seven Soviets, three Bulgarians, two East Germans and seven South Yemenis.

The source said that most of the Cuban forces in Ethiopia were now in the Ogaden since the Cubans, despite Ethiopian requests, have refused to become involved in fighting in the north against secessionist movements in the Red Sea province of Eritrea.

Fighting the Eritreans poses a delicate problem for the Cubans and Soviets since the secessionists are backed both by pro-Soviet and pro-Western governments in the Arab world.