Four more cases of monkeypox have been confirmed in England, bringing the total discovered in recent days to seven.
Three of the cases have been found in London, where two cases were confirmed on Saturday.
The other case has been linked to the North East of England.
The UK Health Security Agency (UKHSA) all four of the new cases were in people who "self-identify as gay, bisexual or other men who have sex with men."
Common contacts have been identified between two of the four, but no link has been found between the latest four cases and the previous three.
They also said none of the new cases have links to a country where monkeypox is endemic.
The (UKHSA) said: "Exactly where and how they acquired their infections remains under urgent investigation."
The first case of monkeypox in the UK was identified on May 6 and the UKHSA is now working with the NHS to try and understand where the outbreak has come from.
The UKHSA said the threat to the general population is low as the virus does not spread easily between people.
The UKHSA does not usually disclose any information regarding the patients who have caught rare infectious diseases but chose on Monday to highlight the sexuality of the latest four cases.
They said: "The most recent cases are in gay, bisexual and other men who have sex with men communities, and as the virus spreads through close contact, we are advising these groups to be alert to any unusual rashes or lesions on any part of their body, especially their genitalia, and to contact a sexual health service if they have concerns."
What is monkeypox?
Monkeypox is a rare viral infection that does not spread easily between people. Initial symptoms include fever, headache, aching muscles, backache, swollen lymph nodes, chills and exhaustion.
A rash can also develop, usually starting on the face before spreading to other parts of the body. It eventually forms a scab which falls off.
Most people recover within a few weeks but severe illness can occur in some individuals.
Dr Susan Hopkins, Chief Medical Adviser, UKHSA, said: “This is rare and unusual. 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.
"We are particularly 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.
"We are contacting any potential close contacts of the cases to provide health information and advice."