At least 25 cases of a dangerous new strain of mpox spreading through the Democratic Republic of Congo have been detected in the eastern city of Goma, mostly in camps housing people fleeing a surrounding conflict, health authorities said on Wednesday.

Congo has seen 20,000 cases and more than 1,000 deaths from mpox, mainly among children, since the start of 2023. Over 11,000 cases, including 443 deaths, have been reported so far this year.

Authorities recently approved the use of vaccines to tackle the upsurge, but none are currently available outside of clinical trials in the country.

The head of the national response team against the mpox epidemic, Cris Kacita, said in an interview that most of the new reported cases were in displaced people camps.

He said cases were infected with a new strain of the virus that is spreading in South Kivu province. Goma is the capital and largest city of the neighbouring North Kivu province.

The World Heath Organization (WHO) and scientists raised the alarm last month about the mpox situation in Congo, including the spread of a new strain of mpox spreading in South Kivu.

Mpox has been endemic in Congo for decades but a new variant of the clade I of the virus emerged last year. It is a viral infection that spreads through close contact, causing flu-like symptoms and pus-filled lesions. Most cases are mild but it can kill.

A different, less severe form of mpox - clade IIb - spread globally in 2022, largely through sexual contact among men who have sex with men. This prompted the WHO to declare a public health emergency that has now ended, although there are still cases and the agency has said mpox remains a public health threat.

"The national biomedical research institute in Goma has sequenced the virus and this proves that the virus has been circulating for a long time in the city of Goma", Kacita said.

"The risk here is the promiscuity in the camps and the speed with which the epidemic is spreading", he warned.

Hundreds of thousands of people who fled conflict in Congo's insurgent-hit east are staying in overcrowded camps in and around Goma.

The number of displaced has increased since a rebel group known as the M23 launched a major offensive in 2022, prompting national and regional military responses that have struggled to stem the militia's advance.