DR Congo authorities have denied Moïse Katumbi permission to enter via air or land.
Democratic Republic of Congo security forces on Monday battled supporters of opposition presidential candidate Moïse Katumbi in the south-eastern city of Lubumbashi, privately-owned Politico website reports.
"The Congolese security forces have deployed considerable means to stop several simultaneous demonstrations by supporters of Moïse Katumbi in several corners of Lubumbashi city," the website said.
The opposition coalition Together for Change had called on their supporters to march on Monday in the capital of Upper-Katanga Province, Lubumbashi, to demand for his return.
Security forces are dispersing demonstrators in central Lubumbashi and no business is reportedly going on.
In several neighbourhoods, the people have barricaded the streets and are burning tyres.
Towards the south, in Bongonga, "gunfire from heavy weaponry can be heard,", several sources in the city told the website.
Early on Monday morning hundreds of women took to the streets of Lubumbashi carrying banners demanding the return of Mr Katumbi and camped outside the governor's office.
DR Congo authorities have denied him permission to enter via air or land.
Mr Katumbi fled into exile in 2016 but wanted to return to register as a candidate in the presidential elections due later this year.
He has spent the weekend in the Zambian city of Kitwe after failing to cross the border into DR Congo.