DRC opposition figures began a two-day meeting yesterday in Belgium to thrash out a common position against Kabila who is widely believed to want a third term, in contravention of the constitution which allows only two.
Tshisekedi, 83, told them they were gathered "as patriots to exchange views on the grave crisis affecting our country."
"More than ever, we must be united to get rid of you know who," he said, referring to Kabila who has been in power since his father's assassination in 2001.
Tshisekedi, who leads the Union for Democracy and Social Progress (UDPS), said the opposition could consider dialogue with Kabila but on conditions -- respect for the constitution, release of political prisoners and oversight by the international community to make sure any agreement was implemented.
More From This Section
The meeting at a hotel in Genval near Brussels was called by Tshisekedi who has been convalescing in Belgium since 2014.
Moise Katumbi, a leading DR Congo opposition figure who has announced his candidacy for the presidency, had been expected to attend but sent his closest advisers instead, organisers said.
Tensions have been soaring in the DRC in recent months over fears that Kabila will postpone elections due to be held late this year as he manoeuvres to extend his time in office.
Tshisekedi, an opposition leader since the rule of strongman Mobutu Sese Seko, came second to Kabila in a fraud-tainted 2011 election.
His UDPS party, struggling with internal divisions, was the only major opposition group to have shown willingness to negotiate with the government.
Tshisekedi last appeared in a video in January looking tired and struggling to speak clearly.