There has been heavy gunfire in the Republic of Congo's capital, Brazzaville, ahead of a visit of exiled former Prime Minister Bernard Kolelas.
Four people are reported dead in the fighting between police and Mr Kolelas' supporters, known as the Ninja rebels.
After eight years in exile, Mr Kolelas is being allowed home briefly to bury his wife who died recently in Paris.
He was ousted in 1997 during a bloody civil war and condemned to death in his absence for alleged war crimes.
The BBC's Christian Tsoumou in Brazzaville says many others were injured in the fighting on Thursday night in the suburb of Bacongo.
He says there has been in a fever of excitement in Bacongo since news emerged of Mr Kolelas' return.
Supporters of his party, the Congolese Movement for Democracy and Development, cannot wait to see their leader after all these years, our correspondent says.
When it became evident that the situation was spinning out of control, party leaders ordered that supporters were not to wear T-shirts bearing Mr Kolelas' image, and to conduct themselves in an orderly way.
The former prime minister is only expected to stay in Brazzaville for a few days, after receiving a short "humanitarian" amnesty to return from President Denis Sassou-Nguesso.
He will attend the funeral of his wife, Jacqueline, who died in France after suffering a brain haemorrhage at the end of last month.
Mr Kolelas, who has been living in Mali and France, has been trying to return home to clear his name since being sentenced in 2001 for alleged war crimes.
The Congolese government is currently reported to be considering granting him a full amnesty.
Despite a 2003 peace deal, some Ninja rebels remain active in the southern Pool region.