The head of Congo's electoral commission says it is not possible to organize presidential elections by the end of this year. The move goes against a political agreement with the opposition, which has accused President Joseph Kabila of clinging to power.

The president of the National Independent Electoral Commission, Corneille Nangaa, made the announcement Friday in Paris.

The election has been delayed since last year, and Kabila's mandate ended in mid-December. Protests that left dozens of people dead helped to push the government and opposition into a Dec. 31 deal that calls for the vote to be held this year — without Kabila as a candidate.

Nangaa said any decision on extending the electoral timeframe would be evaluated with the National Council, civil society and other groups involved in the political agreement.

The United Nations and others have expressed concern about the deal's implementation.

Last month, former U.N. Secretary-General Kofi Annan and nine former African presidents warned of an "acute political crisis" in Congo that threatens both the vast, mineral-rich Central African nation and the continent at large.

Congo's government has said vote preparations need more time.

Kabila came to power after the 2001 assassination of his father, former President Laurent Kabila.