Three new Ebola cases have been reported in Uganda, bringing the total to 12 since the outbreak began in late January, the African Union's health agency said on Thursday.

Ugandan authorities said in mid-February that the outbreak was contained.

But the Ethiopia-based Africa CDC said a new cluster had been identified with three confirmed cases, and two others probable.

A total of 69 people have been identified as contacts and "all are currently being followed up," CDC chief of staff Ngashi Ngongo told reporters.

At least two die of Ebola

The Ebola outbreak in Uganda has left two people dead, a four-year-old child and a nurse, and currently affects five districts.

The epidemic poses "a very important challenge," said Ngongo, adding "everything is being done in the country to intensify the monitoring of contacts."

On Monday, the United Nations launched an appeal to raise $11.2 million to deal with the outbreak after the United States announced the cessation of most humanitarian aid.

There is currently no approved vaccine for Ebola-Sudan, the strain behind the current outbreak.

Vaccination trial

But a vaccination trial for the strain was launched in the country last month. It was praised by the World Health Organization as the "fastest roll-out" of an Ebola vaccine trial in the midst of an epidemic.

Ebola is transmitted between people through body fluids. People who are infected do not become contagious until the appearance of symptoms – mainly fever, vomiting, bleeding and diarrhoea – which occur after an incubation period of between two and 21 days.

More than 15,000 people in Africa have died of Ebola, all six strains combined, in the past half-century.