AKIPRESS.COM - Congolese police on Monday clashed with protesters marching against what they claim is a bid by President Joseph Kabila to extend his mandate, killing at least 17 people and prompting a threat of further sanctions from the United States.

The protest, attended by thousands, came at a time of growing local and international pressure on Kabila to step down when his term of office legally ends in December, Reuters reports.

The opposition accuses him of plotting to extend his tenure in the central African copper producer by delaying elections that were supposed to be held in November until at least next year. His supporters deny this.

"The sad and painful death toll from these barbaric and extremely savage acts is as follows: 17 dead of which three were policemen," said Interior Minister Evariste Boshab, condemning "the use of violence to incite disorder and chaos".

United Nations Secretary-General Ban Ki-moon confirmed the death toll and urged Congolese national security forces to exercise restraint.

The president of opposition party Reformist Forces for Union and Solidarity (FONUS) Joseph Olenga Nkoy said 53 people were killed in the clashes while a local rights official said 25 protesters were shot.

Earlier on Monday, a Reuters witness saw a crowd burning the body of a police officer in the Kinshasa suburb of Limete in an apparent act of retaliation for police gunfire.

Angry crowds torched the offices of politicians loyal to Kabila and tore down giant posters of the president, chanting in French: "It's over for you" and "We don't want you".

Rights groups reported dozens of arrests of protesters and journalists in the capital as well as in Goma and Kisangani, where anti-government marches also took place.

A government spokesman confirmed the detention of opposition leader Martin Fayulu, who suffered a head injury during the march.