The Democratic Republic of the Congo’s government has announced a crackdown on the alleged use of foreign mercenaries by the country’s main opposition leader Moise Katumbi.

Justice Minister Alexis Thambwe Mwamba told a news conference on Wednesday that there was “documented proof” that former US soldiers and South Africans were among the foreigners working for Katumbi in Katanga, the province in which he is based.

“I gave the orders to the PGR [general prosecutor of the republic] to open a judicial case in Katanga,” he said.

Katumbi, the former governor of Katanga, has yet to formally respond to the allegations.

Steve Wenbi, a journalist from a local news agency who attended the conference in the capital Kinshasa, told Al Jazeera that the government launched the probe after authorities arrested a number of suspects in connection with the reported influx of mercenaries, including an ex-US troop and three Congolese.

One of the Congolese arrested is the owner of security company, called Pomba 1. The company, which is based in Katanga’s provincial capital of Lubumbashi, is accused of inviting the foreign mercenaries and is linked to Katumbi, Wenbi said.

He also quoted Mwamba as saying that the government was investigating why more than 600 US citizens, mostly men, had entered the country since October last year.

Lambert Mende, a government spokesman, told Al Jazeera that Pomba 1 was not officially registered as a security company and was therefore operating illegally.

“The interior ministry did not know that it existed as a security company ... It may have been created to bring mercenaries,” he added.

Mende also said that the government has issued arrest warrants for many alleged foreign mercenaries, but a lot of them have been escaping the country to avoid prosecution.

Stephanie Wolters of the Institute for Security Studies, a prominent African NGO, told Al Jazeera: “We don’t know what these ex-American soldiers are allegedly doing for Katumbi, if in fact they are employed by him.

“They could be involved in perfectly legitimate activities. We do believe that one of the members of Katumbi’s security detail who was arrested during a political event in Lubumbashi on April 24 is American.”

The allegations against Katumbi came at a time of increased tensions between him and President Joseph Kabila before presidential elections on November 27.

Katumbi, who recently gained support from 15 political parties in the country, has refused to engage in dialogue between the ruling party and political opposition.

“In the current political context, this allegation will likely be interpreted as being politically motivated, and it will undoubtedly raise tensions, including with the US,” Wolters said.

“If the allegations turn out not to be true, it is explosive that such a serious allegation would be made in an attempt to discredit a political rival. If it is proven that these people were engaged in illegal activities at Katumbi’s behest, the law will take its course.”

Wenbi concluded that he had low hopes that the election would be carried out smoothly.

“We are not in a good situation before the election ... it seems impossible to have an election because of the situation.”

•Source: Al Jazeera. Photo shows DR Congo President Joseph Kabila.