Thousands of opponents of Democratic Republic of Congo (DRC) President Joseph Kabila have gathered in the capital, Kinshasa, to hear a video message from an exiled opposition leader demanding a united front for presidential elections scheduled for December.

Moise Katumbi, a former governor of the DRC’s Katanga province, appeared via Skype to address his supporters on Saturday, a day after another opposition figure Jean-Pierre Bemba won an appeal against an 18-year jail term for war crimes at the International Criminal Court in The Hague.

“We must do everything in agreement with your son and my brother Jean-Pierre Bemba, with Felix Tshisekedi, Vital Kamerhe and the others to present a common candidate at the presidential election,” Katumbi said.

There was widespread applause as he said that was the only way to “bar the path to a third (mandate) wanted by President Kabila”, whose critics suspect he is plotting an illegal third term at the twice-postponed poll.

Katumbi, seen as the opposition’s leading candidate in the election, has been in exile since May 2016, when prosecutors accused him of hiring foreign mercenaries.

The millionaire businessman was sentenced the following month to three years in prison for real estate fraud. He denies all the charges against him.

“I will return to Congo to end the suffering of the Congolese people,” he told the rally, adding that he would form a coalition with the other main opposition leader, Felix Tshisekedi.

Katumbi risks arrest if he returns to his homeland. He has repeatedly promised to do so to contest the election but has yet to make good on the vow.

Last March, he launched in South Africa the Ensemble [Together] platform to overthrow Kabila, who is technically barred by term limits from standing for re-election after his mandate formally ran out in December 2016.

In power since 2001, Kabila has not clearly stated whether he will step aside despite appeals from the international community for him to clearly state that he will not seek re-election.

“We stand against the third term,” Katumbi said in his speech.

Violence flared earlier this year when three rallies calling for Kabila to step down led to more than a dozen deaths. The gathering on Saturday passed off without any incident.

Meanwhile, a UN report in March said a crackdown on demonstrations had led to a death toll of 47 from January 2017 to January of this year.