ROME (AP) _ Prince Karim Aga Khan has resigned from the presidency of the Costa Smeralda consortium to devote more time to his religious duties as the spiritual leader of Ismaili Moslems, according to Italian newspapers.

The prince's decision was announced Saturday at a board meeting at the consortium's headquarters at Porto Cervo, in the Sardinian Costa Smeralda resort area he developed 25 years ago, newspaper reports said Sunday.

The reports said he would devote himself to working with followers in the Third World. Most of the 15 million Ismaili Moslems live in India, Pakistan, Kenya, Tanzania, Iran, Afghanistan and Syria.

The newspaper reports said the prince would probably be succeeded by Franco Grande Stevens, president of Ciga Hotels and Fimpar, the financial group controlled by the Aga Khan that holds majority shares in Ciga and Costa Smeralda Hotels.