The two main Rwandan opposition parties in exile in a statement Monday accused President Paul Kagame of seeking to amend the constitution to have a third term in office.
The Unified Democratic Forces (FDU) and the Rwanda National Congress (RNC) held a joint meeting in the South African city Johannesburg that ended late Sunday.
"The meeting condemns in the strongest terms possible the current manoeuvres by President Paul Kagame to amend the constitution allowing him to stand for a third term...," the parties said in their closing statement.
"The meeting calls upon all Rwandans, all neighbouring countries and the international community to roundly condemn the efforts by President Kagame to endlessly perpetuate himself in power in Rwanda."
Kagame is almost halfway through his second seven-year term in office, but has held the reins of power in Rwanda since 1994. His current mandate expires in 2017.
Earlier this month he tasked three senators to find a solution that would ensure both "change" and "continuity" after 2017, according to local media.
That has been interpreted in several ways, with some observers saying the ruling party will hold a referendum on changing the constitution to allow a third term.
Others say a new president will be elected in 2017 but that Kagame will remain in a yet-to-be-determined position with considerable say over the running of government.