The Catholic church in Congo says its data show a clear winner in Sunday's presidential election, and it calls on the electoral commission to publish the true results in "respect of truth and justice."

The church deployed some 40,000 electoral observers. Congo's electoral regulations forbid anyone but the electoral commission to announce results.

Observers have reported multiple irregularities as the country voted for a successor to departing President Joseph Kabila.

The electoral commission's president on Thursday said it had collected results from about 20 percent of polling stations, while some Congolese expressed doubt that the first results would be released on Sunday as expected.

The internet remains blocked in the Central African country in an apparent attempt by the government to calm speculation.

The outage also hampers election observers' work.