The Royal Free Hospital says the risk to the UK population of cases springing up of monkeypox is "low".
Four more cases have been identified, bringing the total number of confirmed cases in the country to seven, health bosses have said.
The UK Health Security Agency (UKHSA) announced on Monday it is working to find links between the latest cases, which all appear to have been infected in the capital, with links between two already identified.
Cases are being treated at the Royal Free in Hampstead, Royal Victoria Infirmary in Newcastle upon Tyne and Guy’s and St Thomas’.
The virus is usually associated with travel to West Africa and is usually a mild self-limiting illness, spread by very close contact with an infected person.
The virus does not spread easily between people, but the UKHSA is particularly urging men who are gay and bisexual to contact a doctor if they experience unusual rashes or lesions.
The agency said all four of the most recent cases self-identify as gay, bisexual or other men who have sex with men.
The health agency said initial symptoms of monkeypox can also include fever, headache, muscle aches, backache, swollen lymph nodes, chills and exhaustion.
The new cases do not seem to be connected to the previous confirmed cases of monkeypox in the UK which were announced on May 14, or the first UK case announced on May 7, which involved a person who had travelled to Nigeria.
In a statement, the Royal Free said: "A patient diagnosed with monkeypox has been admitted to the infectious diseases unit at the Royal Free Hospital.
"The unit is run by a specially trained team of doctors, nurses, therapists and laboratory staff and is designed to ensure our staff can safely treat a patient with this kind of infection.
"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 an infected person and most people recover within a few weeks. The virus does not spread easily between people and the risk to the UK population is low."
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