Security forces in the Democratic Republic of Congo arrested a senior opposition legislator, a day after he took part in a rally that was held to oppose extension of presidential terms limits, his party said.

Jean-Bertrand Ewanga, the general secretary of the Union for the Congolese Nation (UNC) party, was "arrested this morning very early at his home in Kinshasa after yesterday's meeting," said a statement posted on Twitter by Lydie Omanga, communications chief for UNC president Vital Kamerhe on Tuesday.

Thousands of people demonstrated in the capital on Monday to protest over suspicions that the rulers of the vast central African country intend to amend the constitution and enable President Joseph Kabila to stay in power beyond 2016, when he is due to step down after two five-year elected terms.

Security agents on Tuesday morning took Ewanga before the state prosecutor to hear "the charges against him: inciting hatred, tribalism and contempt of the supreme magistrature," Omanga told AFP news agency, citing prosecution sources.

"Family sources have said that agents of the ANR (National Intelligence Agency) arrived at his home at about 4:30 am (03:30 GMT), accompanied by police officers," the UNC reported.

"They entered the house at 6:00 am with a warrant from the state prosecutor on the grounds of inciting hatred! Ewanga) was led off to an undisclosed location," the party statement said.

During Monday's rally, Ewanga declared that "for us, he (Kabila) must go" by 2016, when presidential polls are due. "We say 'No' to an amendment of the constitution," he told the crowd in one of the main speeches.

The UNC has announced an "emergency meeting" after the arrest, according to Bruno Mavungu, general secretary of the leading opposition party, the Union for Democracy and Social Progress (UPDS), which called for Ewanga's "immediate release".

Kabila, a young soldier, was first rushed into office in 2001 by Kinshasa politicians after the assassination of his rebel-turned-president father Laurent-Desire Kabila by a bodyguard.

A large United Nations mission helped end the conflict and in 2006 played a major part in organising the first democratic polls in the former Zaire, which were broadly declared free and fair.

Five years later, however, fresh elections took place in very different circumstances and sparked an outbreak of serious violence as the opposition cried massive fraud.