(AFP) - Opposition politician Moise Katumbi said Thursday he has asked the UN mission in the Democratic Republic of Congo for protection a day after announcing he was running for president.

"I sent a letter to the (UN mission) MONUSCO seeking their protection because I am in danger, my security is not guaranteed," he told AFP.

"Since this morning my home has been surrounded by security forces," he said. "Two of my body guards were arrested at their homes."

His plea for protection follows Katumbi's announcement he would run against President Joseph Kabila in elections due before the end of the year.

DR Congo authorities are under pressure from the international community to hold the polls as planned in November before Kabila's second -- and constitutionally last -- mandate ends.

On Wednesday, the country's justice minister said he had ordered a probe into allegations that American mercenaries were working for Katumbi.

The politician hit back describing the accusations as a "grotesque lie", adding that his opponents were "simply looking to harm me" and that he would never take up arms to secure power.

On April 24, four members of Katumbi's entourage including an American were arrested in DR Congo's second city Lubumbashi and transferred to Kinshasa.

Justice minister Alexis Thambwe Mwamba accused American "ex-corporal Lewis Darryl of having tried to force a police barrier during an opposition protest" in Lubumbashi on Friday and "having tried to flee during his transfer from Ndjili airport to Kinshasa".

Katumbi, who went over to the opposition in September 2015 after resigning as governor and quitting the president's party, is a major figure in the country's politics.

Popular and charismatic, the 51-year-old wealthy businessman is also head of the prestigious Tout-Puissant Mazembe football club, three-time winner of the African Champions League.

The country has been in crisis since Kabila's re-election in late 2011 in polls marred by irregularities and massive fraud. His second term expires in December and the constitution bars him from standing again.

Last month police in the southeast of the country fired tear gas to break up a demonstration by 5,000 people in the latest unrest triggered by fears that Kabila plans to extend his rule into a third term.

Also on Thursday, Katumbi ally and ex-lawmaker Vano Kiboko was released from prison after serving a 16-month sentence for "inciting tribal hatred".

Kiboko had opposed a revision of the constitution allowing Kabila to run for a third term. He was convicted and sentenced last year.

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