CAIRO — Setting the stage for a potential presidential run by the country's military chief, Egyptian election authorities declared Saturday that more than 90% of voters had approved a new constitution, according to final official results.

Results of the referendum held Tuesday and Wednesday were depicted by the military-backed interim government as a resounding public repudiation of the Muslim Brotherhood, the Islamist movement that Egyptian authorities have spent the last six months trying to crush.

Some election observers, however, expressed strong concern about the climate of political intimidation surrounding the vote. The interim government has taken a series of steps meant to muffle dissent, whether by the Brotherhood or by secular opponents of the military-supported administration.

The official tally of 98.1% in favor generally tracked with unofficial results that had been released two days earlier, which suggested overwhelming backing. But as unofficial results had also indicated, turnout failed to break the 50% barrier.

According to the official results, voter turnout was 38.6%, slightly more than the unofficial tallies had suggested, and more than 5 percentage points higher than turnout in a constitutional referendum last year during the tenure of ousted Islamist President Mohamed Morsi.

Egyptian officials had expressed determination to, at a minimum, get more voters to the polls than had turned out for the Morsi-era vote. Some had voiced hope for a larger voter presence.

The new constitution, drafted by a government-appointed panel, enhances some personal freedoms and promotes women's rights, but also strengthens the hand of Egypt's military. The country's military chief, Gen. Abdel Fattah Sisi, said before the balloting that he would consider a big win to be an expression of the people's will that he run for president.

Since the autocratic Morsi's removal by the military in July — a step that followed massive public demonstrations against him — the government has conducted an unrelenting campaign against supporters of the former president. More than 1,000 Morsi backers have been killed in confrontations with security forces, and the Brotherhood's entire leadership echelon is in jail or on the run.

Morsi himself is on trial for a number of offenses, several of which could carry the death penalty. One of his three trials is to resume Feb. 1.

laura.king@latimes.com

Hassan is a special correspondent and King a Times staff writer.