Shift in S. Yemen is seen as a blow to Soviet sway

South Yememi Marxist President Abdel Fattah Ismail resigned Monday and was replaced by Prime Minister Ali Nasser Muhammad. Arab diplomats said the resignation means a blow to Soviet influence in the vital Gulf of Aden region.

Aden Radio, monitored here, said Mr. Ismail resigned as chief of state of the only Marxist republic in the Arab world because of health reasons. But political sources said he was forced out in a palace coup in favor of the Prime Minister, who favors good relations with neighboring Saudi Arabia and North Yemen.

The radio said the Central Committee of the ruling Marxist National Front Party elected Mr. Muhammad to replace President Ismail as secretary-general of the party and asked him to take up the duties of the chairman of the People's Supreme Council in addition to his duties as prime minister -- making him the supreme ruler.