Exiled DR Congo opposition leader Moise Katumbi said on Friday he was seeking to return home by road from Zambia to file a presidential election bid after the authorities barred his plane from landing in his provincial stronghold.
Katumbi has been living in self-imposed exile in Belgium since May 2016 after falling out with President Joseph Kabila.
He had planned to fly by private jet from Johannesburg to Lubumbashi, the capital of Katanga province, to lodge his application to stand in long-delayed elections in December -- a move that would heap pressure on Kabila.
But the city's mayor said Thursday that Katumbi would be refused entry, while the public prosecutor's office said Katumbi had been charged with "harming the state's domestic and external security" and would be immediately arrested if he returned.
Katumbi's spokesman Olivier Kamitatu said "authorisation to fly over and land had been refused by Kinshasa".
"We will take off in the direction of (Zambian city) Ndola to take the road to Lubumbashi," Kamitatu tweeted.
Katumbi told AFP later that he had arrived in Ndola at around 0900 GMT and was heading to the border post of Kasumbalesa. The drive to the frontier takes more than six hours, according to local sources.
At least two police checkpoints were set up to screen access to Lubumbashi's airport on Friday and the main road to Zambia had been blocked by a truck, an AFP journalist said.
"As you can see, we are waiting for the president (Katumbi), but those in power do not want him to be there," said Katumbi's brother Abraham Soriano.
The former governor of the mineral-rich southern province of Katanga had once been close to Kabila before the two had a falling-out.
Katumbi, 53, already faced potential arrest after being handed a three-year jail term in absentia in June 2016 in a case of alleged property fraud.
He has also been accused of hiring mercenaries and for possessing an Italian passport -- Congolese law does not allow dual nationality. He denies the charges in both of those cases.
Another rival of Kabila, former warlord and ex-vice president Jean-Pierre Bemba, 55, returned home this week. He officially launched his bid for the presidency on Thursday.
The Democratic Republic of Congo has never known a peaceful transition of power since it gained independence in 1960 -- and some experts fear that the December 23 elections may trigger a bloody conflict.
Kabila, 47, has been at the helm since 2001, presiding over a vast mineral-rich country with a reputation for corruption, inequality and unrest.
He was scheduled to stand down at the end of 2016 after his second elected term, technically the last permitted under the constitution.
Kabila has refused to spell out whether he will seek a new term in the vote. Candidates must submit their applications by August 8 and physically be in the country to do so.