The highest-ranking priest in Congo's powerful Catholic Church on Sunday urged churchgoers in Kinshasa to boycott the country's first democratic elections in nearly 50 years if authorities do not correct alleged irregularities.

The letter from Cardinal Frederick Etsou, read out at Masses in the capital, came a day after the Catholic Bishops' Conference warned it might not recognize election results, saying fears of manipulation and fraud appear well-founded.

Among concerns are the disappearance of 1.2 million names from the voters' roll — Cardinal Frederick Etsou due to a technical problem, according to the Independent Electoral Commission, which denies there are irregularities.

"We invite our people to be ready to abstain from these elections, if the established irregularities are not corrected," Cardinal Frederick Etsou said in his pastoral letter.

Half of Congo's 63 million people are Catholic and the church is about the only functioning institution in this country where the assassination of the first elected leader in 1960 was followed by decades of corrupt dictatorship which ended in a civil, then regional, war that killed some four million people.