Four more cases of monkeypox have been detected in England, health officials have said.
The new cases of the rare viral infection do not seem to be connected to the previous two confirmed cases announced on 14 May and an earlier case on 7 May, said the UK Health Security Agency.
Of the four new ones, three were in London and one linked case was in the North East. The four all appear to have been infected in the capital.
It means there are currently seven confirmed cases in the UK, diagnosed between 6 and 15 May.
The first case was a person who had recently travelled to Nigeria, which is where they were believed to have contracted the infection, before travelling to the UK.
The two cases announced on 14 May live together in the same household. They are not linked to the earlier case.
All four of the new cases self-identify as gay, bi-sexual or other men who have sex with men, the UKHSA said.
They have the West African clade of the virus, which is mild compared to the Central African one, it added.
Common contacts have been identified for two of the four latest cases.
"This is rare and unusual," said the UKHSA chief medical adviser Dr Susan Hopkins of monkeypox in Britain.
"UKHSA is rapidly investigating the source of these infections because the evidence suggests that there may be transmission of the monkeypox virus in the community, spread by close contact."
Dr Hopkins said the agency is urging men who are gay and bisexual to be aware of any unusual rashes or lesions and to contact a sexual health service without delay.
The agency said there is no link to travel to a country where monkeypox is endemic, and exactly where and how they acquired their infections is under investigation, including whether they have further links to each other.
Those patients needing medical care are all in specialist infectious disease units at the Royal Free Hospital, Royal Victoria Infirmary in Newcastle upon Tyne, and Guys' and St Thomas'.
Monkeypox is a viral infection usually associated with travel to West Africa.
It is usually a mild self-limiting illness, spread by very close contact with someone with monkeypox and most people recover within a few weeks. However, severe illness can occur in some people.
The virus does not spread easily between people and the risk to the UK population is low, according to the agency.
Initial symptoms of monkeypox include fever, headache, muscle aches, backache, swollen lymph nodes, chills and exhaustion.
A rash can develop, often beginning on the face, then spreading to other parts of the body including the genitals.
The rash changes and goes through different stages, and can look like chicken pox or syphilis, before finally forming a scab, which later falls off.