By Aaron Ross
KINSHASA (Reuters) - More than 300 people, including opposition leaders, remain in detention in Democratic Republic of Congo after protests last month, reinforcing concerns that President Joseph Kabila plans to cling to power beyond his legal mandate.
Kabila is constitutionally barred from seeking a third term next year after winning disputed elections in 2006 and 2011.
With growing signs of popular opposition to any attempt to prolong Kabila's mandate in the vast central African country, his ruling coalition has been weakened by a string of high-profile defections, particularly in his home province of Katanga.
In four days of anti-government protests last month, security forces killed at least 40 people and parliament was forced to drop plans to require a census before next year's vote that critics said was aimed at delaying the election and keeping Kabila in power.
The Office of the United Nations High Commissioner for Human Rights (OHCHR) has expressed alarm over a wave of detentions prompted by the protests, saying some prisoners had been held for three weeks with no access to a lawyer.
Among opposition leaders and former Kabila allies detained are several officials close to the governor of the copper-producing Katanga province, Moise Katumbi, with whom the president has fallen out.
Katumbi publicly came out against a third term for Kabila in December and was then stripped of his post as provincial head of Kabila's political party.
Allies of Katumbi, including Jean-Claude Muyambo -- the head of a political party that withdrew from Kabila's coalition -- have been arrested on charges ranging from the improper sale of real estate to embezzlement.
The government denies the arrests were politically motivated and says many of those detained are charged with pillaging during the demonstrations.
"WOUNDED WILD BEAST"
But Kabila's critics and some political analysts say the detentions suggest increasing desperation on his part.
"He's politically weakened and increasingly isolated," said Pascal Kambale, former Congo country director for the Open Society Initiative for Southern Africa. "He's as dangerous as a wounded wild beast."
Congo has never had a peaceful transition of power since winning independence from Belgium in 1960.
OHCHR said last Friday it believed at least 11 prisoners, including human rights campaigner and opposition activist Christopher Ngoyi, were being held incommunicado.
Ngoyi's family and colleagues said he had not been heard from since he was detained in Kinshasa on Jan. 21. "We haven't seen him. We haven't spoken to him," his son Patrick told Reuters on Saturday.
Government spokesman Lambert Mende has told a local radio station Ngoyi is in police custody and awaiting a court appearance on charges of pillaging and incitement to racial hatred, adding that Ngoyi's family "knows where he is".
Roman Catholic Bishop Fridolin Ambongo said the government's hardline tactics could trigger further street violence.
"We fear its last word will be an act of madness that could lead to the situation getting out of control because the people will not give up," he said. "If there is only force as a response, there will be tragic consequences in our country."
(Additional reporting by John Irish in Paris and Bienvenu-Marie Bakumanya in Kinshasa; Editing by Daniel Flynn and Gareth Jones)