BANGUI, Central African Republic (AP) _ Government officials decided Saturday to postpone Sunday's presidential elections, citing a shortage of election materials, President Ange-Felix Patasse announced.

Speaking on state radio late Saturday night, Patasse said the vote _ which has already been delayed once _ would be rescheduled for Sept. 19, one week later than planned.

He said a shortage of voting materials had caused the delay.

``I know that many voters have not got their cards yet. I also know that there is still a lot to do in printing the ballot papers,'' he said.

Olu Yene Adenedji, the head of the U.N. mission in Central African Republic, said the decision followed hours of meetings among government officials, members of the U.N. mission, National Electoral Commission officials and members of the national assembly.

He said all had agreed to the postponement, which was announced a day after riots that left two Patasse supporters stoned to death and dozens injured.

The incident occurred on the last day of campaigning. Thousands of supporters of Patasse's Movement for the Liberation of the People of Centrafrique were marching through the capital, Bangui, when they were attacked by about 100 stone-throwing supporters of former President Andre Kolingba. Kolingba is one of the nine candidates trying to oust Patasse.

The streets of Bangui were quiet Saturday. It was not clear if the decision to postpone the vote was linked to the violence.

Patasse is widely expected to be re-elected to a second six-year term. Opposition candidates have accused him of rigging the vote in his favor.

If no single candidate earns 50 percent of the vote, the top candidates will go on to a second round of voting, which had been planned for Oct. 3.