The monkeypox outbreak could be the "peak of the iceberg" as 257 cases have been recorded worldwide, a World Health Organisation boss has warned.
Pandemic preparedness and prevention chief Sylvie Briand said there could be "many more cases" that have gone undetected in certain communities.
The first UK cases were flagged up on May 7.
WHO has now received reports of 257 confirmed cases and around 120 suspected ones across 23 countries, it said in an update on Sunday.
There has been no reported fatalities so far.
Speaking at the World Health Assembly in Geneva on Friday, Ms Briand said: "We don’t know if we are just seeing the peak of the iceberg [or] if there are many more cases that are undetected in communities.
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“We are still at the very, very beginning of this event."
“We know that we will have more cases in the coming days,” she said.
However, the expert added it is "not a disease the general public should worried about".
"It is not Covid or other diseases that spread fast."
As part of its update yesterday, WHO said the virus constitutes a "moderate risk" to overall public health, despite cases being reported in nations the disease is not typically found.
It said: "The public health risk could become high if this virus exploits the opportunity to establish itself as a human pathogen and spreads to groups at higher risk of severe disease such as young children and immunosuppressed persons."
WHO also said that the sudden appearance of monkeypox at once in several non-endemic countries suggests undetected transmission for some time and recent amplifying events.
The agency added that it expects more cases to be reported as surveillance in endemic and non-endemic countries expands.
Monkeypox is an infectious disease that is usually mild, and is endemic in parts of west and central Africa.
It is spread by close contact, so it can be relatively easily contained through measures such as self-isolation and hygiene.
Most of the cases reported so far have been detected in the UK, Spain and Portugal.
"The vast majority of reported cases so far have no established travel links to an endemic area and have presented through primary care or sexual health services," the U.N. agency said.
