Ferhat Abbas, 86, who helped lead Algeria to independence from France and then spent many years under house arrest until he was finally rehabilitated by the new regime, died here Dec. 24. The cause of death was not reported.

His death was announced during a congress of the ruling National Liberation Front. The 5,000 delegates observed a moment of silence in tribute.

Mr. Abbas, a pharmacist by profession, was profoundly influenced by French culture. Despite his strong Moslem convictions, he backed independence only after spending years trying unsuccessfully to integrate the European and Arab communities. He was a local official in the French administration in northeastern Algeria in the 1930s but by the end of that decade his political sentiments had changed radically toward nationalism.

His "Manifesto of the Algerian People," published in March 1943, is considered a turning point in the Algerian independence movement. It called for liberty and equality for Moslems in Algeria and for political autonomy as a sovereign nation. At the time, Algeria was a French department, legally as much a part of France as is Paris.

The war for independence began Nov. 1, 1954. In September 1958, Mr. Abbas was named president of the provisional government that was declared by the National Liberation Front. He held the post through 1961, during some of the bloodiest fighting between Algerian and French forces.

After independence was won in 1962, Mr. Abbas was elected president of the National Assembly, the Algerian parliament. Initially he supported Ahmed Ben Bella, the new state's first president. But in 1963 he resigned in protest against Ben Bella's moves to develop a socialist state and to keep political power in the hands of the National Liberation Front.

Mr. Abbas was placed under house arrest and remained so under President Houari Boumedienne, who ousted Ben Bella and speeded up the country's development into an authoritarian state with a centrally planned economy.

Boumedienne's successor, President Chadli Bendjedid, has tried slowly to dismantle some of Boumedienne's state apparatus, while opening the country up to Western investment.

Last year Mr. Abbas was released from house arrest and on the 30th anniversary of the outbreak of the war of independence he was decorated and officially rehabilitated.