Democratic Republic of Congo (DRC) opposition leader Moïse Katumbi arrived in South Africa to receive medical treatment last night (20 May). The presidential candidate had been in hospital after police fired tear gas at him and a number of his supporters outside the prosecutor's office in the DRC's second city, Lubumbashi, on 13 May.

The former governor of the powerful Katanga province was granted permission to travel after he "asked for conditional release covered by a medical certificate saying he needed appropriate care abroad. The prosecutor agreed to the request and authorised his departure," Justice Minister Alexis Thambwe Mwamba said.

An arrest warrant was issued for Katumbi on 19 May, but he was allowed to travel on condition that he returns to the DRC to face the charges against him. Katumbi stands accused of hiring foreign mercenaries to destabilise the government in Kinshasa – a charge that he vehemently denies.

Katumbi has denounced the allegations and critics say they are an attempt to force his presidential bid to grind to a halt, further strengthening President Joseph Kabila's grip on power. The DRC is due to hold presidential elections in November this year and Kabila is expected to step down when his mandate expires at the end of 2016, as per the Congolese constitution.

Political tensions are running high in the country as voters clamour to exercise their democratic right. Kabila has been in power since 2001 and is nearing the end of his second full term.

Earlier this month, the US Embassy in Kinshasa told IBTimes UK that it is "actively" considering sanctions against senior Congolese officials if Kabila stays in power beyond the legal limit set by the constitution. Henri Mova Sakani, the secretary general of the ruling People's Party for Reconstruction and Development (PPRD), hit back saying the government would not cower at the prospect of sanctions.

"You can come up with anything you like – sanctions or whatever. You won't scare us," he told a crowd of people on 17 May.

Last year, Kabila called for a national dialogue to prepare for the upcoming elections, "but no resolution seems imminent", Chatham House's Consulting Fellow for the Africa Programme, Ben Shepherd noted on 20 May.

As election-related "anger simmers among an impoverished and disenfranchised population," said Shepherd, "An entrenched national leadership is indulging in heavy-handed harassment of political opponents."

The growing political crackdown has also been criticised by the US. In a statement tweeted by the US Embassy in Kinshasa on 21 May, it said the Congolese government cannot call for a dialogue among stakeholders while simultaneously "harassing, arresting and jailing those individuals expected to participate." It called on all parties to engage in a "credible dialogue."