Egyptian President Anwar Sadat, trying to silence a "campgin of doubt" about his leadership, won almost unanimous popular backing in a referendum to bar his opponents of the left and right from politics, the government announced yesterday.

The Interior Ministry said the tough measures proposed by Sadat were approved by 98.29 percent of the voters in the Sunday balloting. It said 9,202,553 voted in favor and 159,578 people voted "no." The turnout was reported as 85.4 percent.

The voters approved proposals calling for barring Communists from executive posts in the government, news media or trade unions and a similar ban on rightsits and persons spreading "false and malicious rumors . . . or . . . the spirit of defeatism."

In other Middle East developments:

Isreali occupation authorities are looking into prospects of expropriating more Arab and to build six big Jewish settlements on the West Bank, official sources said in Tel Aviv.

King Hussein returned to Jordan after two days of private talks in Saudi Arabia aimed at rebuilding Arab solidarity, informed sources in Amman said.

A terrorist group called the Sons of South Tebanon, which took credit for Saturday's terrorist attack at Paris' Orly Airport, warned that it will strike again at France for sending troops to Lebanon as part of the U.N. peacekeeping force.