A Norwegian woman who contracted the Ebola virus while working for Doctors Without Borders in Sierra Leone was cured and released from an isolation unit Monday.

"Today I am in good health and am no longer contagious," Silje Lehne Michalsen told reporters just minutes after Oslo University Hospital announced she had recovered.

"I feel very lucky and actually it doesn't feel like I have had Ebola," the 30-year old medical charity worker added with a smile as she hugged one of the medical staff.

She had been kept in an isolation ward since her repatriation from Sierra Leon and given an experimental treatment. The medical team did not disclose details of the treatment.

Michalsen was infected with the deadly virus which has claimed more than 4,500 lives when she was working in Sierra Leone's second city Bo.

In her first public appearance since her recovery, she criticised the reaction of the international community to the disaster sweeping West African countries.

"For three months I saw the total absence of an international response. For three months I became more and more worried and frustrated," she said.

"The clock is ticking and the number of dead is increasing. We should act and act now."