ALGIERS (AP) _ Algerian voters overwhelmingly approved a new constitution that paves the way for a multi-party system for the first time since independence from France in 1962.

More than 70 percent of the 10.4 million voters in Thursday's balloting voted for the constitutional change, according to results announced today by the Interior Ministry.

The constitution extends the process of political and social reform that President Chadli Bendjedid promised after a week of riots last October left 176 people dead by official count. Government offices were the main targets of rioters.

About 80 percent of the 13 million voters in this former French colony in North Africa cast ballots, the ministry said.

Interior Minister Aboubakr Belkaid said the new constitution ''opens the way to a new era.'' He said it will allow his country ''to know more democracy, to assure public and individual liberties, and to establish the sovereignty of the law.''

Although it does not specifically authorize political parties to compete with the ruling National Liberation Front in this nation of 25 million, the new constitution declares ''the right to create associations of a political character.''

Since Bendjedid, 59, announced the draft constitution, various groups have begun forming. Among them are the leftist Democratic Union, the Islamic Salute Front and the Berber's Rally for Culture and Democracy.

Ahmed Mahsas, a former agricultural minister, announced formation of the Union of Democratic Forces on Thursday, the official Algerian Press Service reported.

It was the third national referendum in less than four months.

In November, 92 percent of the voters approved political reforms that began reducing the power of the ruling party, Algeria's only legal political organization. The next month, about 81 percent elected Bendjedid to a third five-year term.

October's riots were rooted in economic problems brought by low world prices for oil, the nation's chief export. Many Algerians blamed the centralized, socialist government for failing to solve the problems.

The proposed constitution also guarantees freedom of expression and, within limits, the right to strike. It would restrict the army to defending the ''national independence, the unity and territorial integrity of the country.''

Under the current charter, the army has a role in ''development of the country and the building of socialism.''

Also dropped is a declaration that ''the Algerian state is socialist.'' The new text does not refer to socialism.

However, Islam would remain the state religion and Arabic the official language.