Sir Seewoosagur Ramgoolam, 85, the governor general of Mauritius who had served as prime minister of that Indian Ocean island nation from 1968 to 1982, died Dec. 15 in Port Louis, the Mauritian capital. The cause of death was not reported.

Sir Seewoosagur, who was knighted in 1965, became his nation's first prime minister after it gained independence from Britain in 1968. He held office until his pro-western coalition government, headed by the National Alliance Party, was defeated in the 1982 parliamentary elections, failing to win any of the 62 seats at stake.

The victorious leftist alliance of the Mauritian Militant Movement and Socialist Party campaigned on a promise to seek the return of Diego Garcia, an island used by the United States as a military base.

From 1976 to 1977, Sir Seewoosagur was chairman of the Organization of African Unity. He was vice chairman of the 1977 Afro-Arab Summit.

President Reagan issued a statement saying that Sir Seewoosagur "will be greatly missed and was respected as both an outstanding statesman who led Mauritius to independence and as a stalwart defender of traditional democratic values."

Sir Seewoosagur was born in Mauritius to Indian immigrants. He studied medicine in Britain and entered politics as a member of the legislative council in 1940. Before his country achieved independence, he was mayor of Port Louis and served as finance minister. He sought to play a moderating role among Mauritian political parties and to diversify an economy heavily dependent on sugar cane.

Mauritius, which has an area of 720 square miles, lies more than 1,000 miles off the coast of eastern Africa and was once the home of the dodo bird, now extinct. It was a French colony until 1810, when the British took it. At the time of independence, the majority of its 800,000 people were Hindus, with large numbers of Muslims, Chinese and Creoles, a mulatto middle class descended from slaves imported by France. There also was a white community of about 10,000 Franco-Mauritians.

In private life, Sir Seewoosagur was board chairman and president of the Mauritius Society for the Prevention of Cruelty to Animals and a first patron of the World Federation for Protection of Animals.

He was married and had two children.