KINSHASA, Oct 10 (Reuters) – The longtime head of Democratic Republic of Congo’s elections commission has resigned, the presidency said in a surprise announcement on Saturday, adding to uncertainty over a presidential poll due to be held next year.

President Joseph Kabila has ruled the vast Central African nation for 14 years but is barred by the constitution from standing for another term. However, critics and the opposition claim he is seeking to manipulate a packed elections calendar to prolong his rule.

“The President of the Republic informs national and international opinion of the resignation of Father Apollinaire Malumalu … for health reasons,” the head of Kabila’s press office Jacques Mukaleng Makal announced on state-run television.

He gave no further details of the decision.

Malumalu, a Catholic priest, headed the elections commission during two previous presidential polls in 2006 and 2011 that Kabila won amid opposition accusations of fraud.

Recent months have seen a rapid erosion of support for the president among some of his key supporters.

The G7, a grouping of seven political parties that previously formed part of Kabila’s coalition, on Saturday signed an agreement pledging to support a single candidate in next year’s election.

Moise Katumbi, the powerful governor of copper-rich Katanga province, stepped down from his government post and resigned from the ruling party last month, accusing Kabila of resorting to increasingly repressive tactics to hang onto power.

Human Rights Watch this week accused police and ruling party officials of recruiting thugs to attack a peaceful opposition rally on Sept. 15 in which more than a dozen protesters were injured.

Information Minister Lambert Mende has repeatedly said Kabila intends to respect the constitution, but the president has so far not commented publicly on his political future. (Reporting by Bienvenu-Marie Bakumanya; Writing by Joe Bavier, editing by David Evans)