THREE new cases of Ebola have been confirmed in a city of more than one million people in the Democratic Republic of Congo, sparking fears the deadly virus is spreading in urban areas.

The confirmed cases are in Mbandaka, where one instance of infection was confirmed earlier in the week, the country’s health minister said.

There are now 17 confirmed Ebola cases in this outbreak, including one death, plus 21 probable cases and five suspected ones.

The World Health Organisation (WHO) decided not to declare the outbreak a global health emergency, but it called the risk of spread within Congo “very high” and warned nine neighbouring countries that the risk to them was high.

WHO said there should be no international travel or trade restrictions.

The outbreak is a test of a new experimental Ebola vaccine that proved effective in the West Africa outbreak a few years ago.

Vaccinations are expected to start this week, with more than 4000 doses already in Congo and more on the way.

A major challenge will be keeping the vaccines cold in the vast, impoverished country where infrastructure is poor.

While Congo has contained several Ebola outbreaks in the past, they were primarily based in remote rural areas.

The virus has twice made it to the capital of 10 million people, Kinshasa, but the spread was rapidly halted.

Health officials are trying to track down more than 500 people who have been in contact with those feared infected, a task that became more urgent with the spread to Mbandaka, which lies on the Congo River, a busy traffic corridor, and is an hour’s flight from the capital.

The WHO, which was accused of bungling its response to the West Africa outbreak – the biggest Ebola outbreak in history with more than 11,000 deaths – appears to be moving swiftly to contain this latest epidemic, experts said.

There is “strong reason to believe this situation can be brought under control,” said Dr Robert Steffen, who chaired the WHO expert meeting on Friday. But without a vigorous response, “the situation is likely to deteriorate significantly”.