{WASHINGTON :Congo’s leading opposition candidate for president said Monday he was poisoned as part of a government plot to kill him, a dramatic claim almost certain to escalate tensions even further over upcoming elections in one of Africa’s largest countries.}

In an interview with The Associated Press, Moise Katumbi said he was roughed up by police in May who injected him with an unknown substance outside a courthouse in the city of Lubumbashi.

“Their plan was to kill me,” Katumbi said, “because they are scared about my popularity.”

Katumbi said the directions came from the highest levels of Congo’s government, but he did not provide details about whom he specifically believes was responsible.

Katumbi and other critics of President Joseph Kabila have expressed concern that the election set for November will be delayed so that Kabila will stay in power longer. Kabila is supposed to leave office in December, but he has not publicly declared his intentions.

Congo’s communications minister, Lambert Mende, was unavailable to comment on Monday, but he had previously dismissed allegations Katumbi had been harmed by the police. He noted that Katumbi was allowed to leave Congo for medical treatment elsewhere.

“If the objective was to kill him as he claims, why let him go and vilify us in the press?” Mende said in a recent interview with a radio station.

Since Congo won independence from Belgium in 1960, there has never been a peaceful, democratic transition of power in the country. Kabila has been in office since 2001, taking over less than two weeks after his father, President Laurent Kabila, was shot by a bodyguard in the presidential palace. He was elected president in 2006 and again in 2011. Kabila is barred by Congo’s constitution from a third term.

Congo, which has vast mineral deposits, is nearly one-fourth the size of the United States and has a population of more than 79 million. More than a decade after Congo’s back-to-back civil wars ended, the country’s east remains in discord. Scores of militias and armed groups are blamed for violence against civilians, and nearly 2.7 million Congolese are internally displaced as a result, according to figures compiled by the United Nations.

Katumbi, a former governor of Congo’s southern Katanga and longtime president of the TP Mazembe soccer team, had been summoned to court on allegations he hired mercenaries to be his bodyguards. He called the allegations a “big joke.”

Thousands of his supporters had gathered outside the venue on May 13 and police fired tear gas to disperse them and Katumbi fell ill. He was hospitalized in Lubumbashi with an unspecified ailment when authorities formally charged him.

He was medically evacuated to South Africa and has since sought treatment in London and Germany.

Katumbi hadn’t discussed the circumstances of his illness. He told the AP that he needed oxygen for a week to help him breathe. The substance caused a blood infection, Katumbi said, and he pledged to release laboratory results when tests are complete.

“I’m going to show to everyone, to tell them what is going on in the Congo,” Katumbi said. “This is not anymore politics.”