BRAZZAVILLE, Republic of Congo (AP) — Six men were injured in clashes between police and opponents of a planned referendum to allow Republic of Congo's longtime president to run for another term, a local official said.

The clashes occurred Saturday in the country's second largest city, Point-Noire, said Alexandre Honore Paka, the city's administrator. Six "uncontrollable" young men had been injured but were receiving treatment and "doing well," said Paka in a statement.

"All other information is nothing but the fruit of the imaginations of those who want to create psychosis in our city, a haven of peace," Paka said.

At a press conference Sunday, however, opposition leader Andre Okombi Salissa said 13 people had been hospitalized.

By the time his current term ends next year, 71-year-old President Denis Sassou N'Guesso will have served more than 30 years as leader of this Central African nation, though not continuously.

He first ruled the country of more than 4 million people from 1979 until a 1992 election defeat. He then seized power in 1997, following a civil war in which his rebel forces ousted the president. He was elected in 2002 and then again in 2009 for what was to be his second and final seven-year term.

The referendum, scheduled for Oct. 25, calls for the limit of two terms to be scrapped as well as changing a rule stating candidates must be no older than 70 years.

Okombi Salissa and other opposition leaders have called on their supporters to block the referendum and are planning to start a campaign of "civil disobedience" on Tuesday pushing for Sassou N'Guesso's resignation.

Prosecutor Andre Galaka Oko issued a statement Saturday warning of "very heavy penalties" for those who threaten public order.

In Brazzaville, families have been stocking up on food and expressing concern about violence in the coming days.