UK health officials said there had been 11 more confirmed cases of the rare monkeypox virus in the country, taking the total to 20

The announcement came as France, Belgium and Germany reported their first cases of monkeypox, joining several other European and North American nations in detecting the disease, which is endemic in parts of Africa.

The UK Health Security Agency (UKHSA) said it had "detected 11 new cases of monkeypox in England", up from a total of nine.

"Most cases are mild and I can confirm we have procured further doses of vaccines that are effective against monkeypox," Health Secretary Sajid Javid tweeted.

The UKHSA's chief medical adviser, Susan Hopkins, said that she expected "this increase to continue in the coming days and for more cases to be identified in the wider community".

She particularly urged gay and bisexual men to look out for symptoms, saying a "notable proportion" of cases in UK and Europe came from this group.

The UKHSA said monkeypox had not previously been described as a sexually transmitted infection.

The World Health Organization (WHO) said it was also investigating the fact that many cases reported were people identifying as gay, bisexual or men who have sex with men.

Symptoms of the disease include fever, muscle aches, swollen lymph nodes, chills, exhaustion and a chickenpox-like rash on the hands and face.

It can be transmitted through contact with skin lesions and droplets of a contaminated person, as well as shared items such as bedding and towels.

The first UK case was announced on May 7, in a patient who had recently travelled to Nigeria.

Two more cases were reported a week later, in people in the same household. They had no link to the first case.