Eleven people have been killed in the Democratic Republic of Congo during protests to demand that President Joseph Kabila step down after his mandate expired, according to the government's spokesman.

Nine people died in the capital Kinshasa, the spokesman said, while a protester and a policeman were killed in the second city Lubumbashi according the region's governor, the AFP news agency said on Tuesday.

"In Kinshasa there were nine dead, not a single one more," Lambert Mende said as Kabila appeared set to stay on despite the conclusion of his mandate.

Jean-Claude Kazembe, Lubumbashi's governor, said that along with the two fatalities, three people had been hurt in clashes in the city.

Demonstrators took to the streets earlier in the day, beating on improvised drums and shouting slogans against Kabila, 45, who has led the country since 2001.

There were reports of gunfire in several areas in the capital. A muffled explosion was also heard in the posh quarter of Gombe, where the presidential palace is located. Residents said tear gas shells were fired in other areas.

The UN's mission in the DRC, MONUSCO, had earlier said it was investigating reliable reports that around 20 people had been killed in the country's capital during protests.

Kabila's second term officially expired on Tuesday.

Against this backdrop, Etienne Tshisekedi, the opposition leader, called on the Congolese people to peacefully resist Kabila.

"I launch a solemn appeal to the Congolese people to not recognise the ... illegal and illegitimate authority of Joseph Kabila and to peacefully resist [his] coup d'etat," Tshisekedi said in a video posted on YouTube.

The declaration appeared to be an effort by him and opposition leaders to re-inject themselves into the political picture after they originally declined to call for mass protests.

READ MORE: Is the DR Congo on the brink of collapse?

Talks on a peaceful transition are in limbo, prompting fears of new violence in the unstable, mineral-rich nation.

Kabila, who has been in power for 15 years, is constitutionally barred from seeking a third term, but under a recent constitutional court order, he may stay on until a successor is chosen.

Election schedule

The ruling party and some opposition leaders have agreed to schedule an election in April 2018, at the earliest, leaving Kabila in office until the vote.

But the main opposition bloc rejects this plan.

A democratic handover would break new ground for DRC's 70 million people who, since independence from Belgium in 1960, have never witnessed a democratic transfer of power following elections.

The president has been in office since his father, Laurent Kabila, was assassinated in 2001.

He was elected in 2006, and again in 2011, in a poll the opposition decried as rigged.

Source: News agencies