DAKAR (Reuters) - The United Nations mission in Mali has canceled plans to renew a contract with a private clinic providing care to its peacekeepers after a case of Ebola was missed and spread from there.

This second Ebola alarm in Mali, coming just as it seemed to have contained its first case last month, raised doubts about the country's ability to protect itself from the epidemic that is ravaging three other states in West Africa. More than 5,000 people have died, almost all in Liberia, Sierra Leone and in Guinea, which shares an 800 km (500 mile) border with Mali.

The U.N. mission in Mali, whose peacekeepers are helping to protect the nation against Islamist rebels, reversed on Saturday a decision taken earlier in the week to renew the contract with the Pasteur Clinic in Bamako to care for sick or injured troops.

A U.N spokesman said the decision was taken "due to prevailing circumstances" but gave no further details.

It followed the death in the clinic in late October of an elderly imam, or Muslim religious leader, from Guinea. The sick man was never tested, but his case directly led to a chain of confirmed deaths from Ebola, including a 25-year-old nurse who treated him and a woman who washed his dead body.

The clinic, one of Bamako's best known and used by expatriates and the country's elite, denies any wrongdoing. It says it followed all its procedures for treating Ebola and that the imam never showed any signs of the fever.

On Tuesday last week, Mali's health minister declared there were no more confirmed cases in the country after it appeared to have successfully contained its first Ebola case of an infant girl who died last month.

But by nightfall the same day, the 25-year-old nurse from the clinic had died of the disease and authorities are now trying to trace over 400 potential fresh contacts.

President Ibrahim Boubacar Keita has ordered an enquiry.

Ibrahima Fall, World Health Organisation representative in Mali, said the Pasteur Clinic - which has no connection to the Paris-based Institut Pasteur - made "a terrible mistake" by not alerting authorities to the case of the sick Guinean imam, who would have been showing Ebola-like symptoms.

He said it was WHO officials tracing reported deaths in Guinea who had discovered this case in Mali.

Mali's Ebola response leader, Samba Sow, said the clinic did not tell him of a second suspected Ebola case once he got there. "It is something we would like to have known," he said.

Aid workers and diplomats in Bamako cite delays and obstacles in setting up Sow's Ebola-response team and poor communication within government over the latest case.

(By David Lewis; Additional reporting by Joe Penney, Colin Baker and Tiemoko Diallo Bamako; Editing by Pascal Fletcher and David Stamp)