Health authorities in Portugal identified nine new cases of the monkeypox viral infection, taking the total to 14, while in Spain authorities on Thursday reported the first seven cases.
Monkeypox is a rare viral infection similar to human smallpox, though milder. Symptoms include fever, headaches and skin rashes.
The outbreaks in Britain, Portugal, Spain and the United States have raised alarm because the viral disease, which spreads through close contact and was first found in monkeys, mostly occurs in West and Central Africa, and only very occasionally elsewhere.
The nine patients confirmed in Portugal are stable and being closely monitored, Portuguese health authority DGS said late on Wednesday, adding that experts were trying to "identify chains of transmission and potential new cases".
Most cases in Portugal were reported in and around the capital Lisbon, DGS said.
Spain reported its first seven confirmed cases and 22 possible cases, all in the central region of Madrid, local health authorities said.
"It's possible we will have more cases in the coming days," Madrid regional public health chief, Antonio Zapatero, told Onda Cero radio station.
The Portuguese health authority has asked those with "suspicious symptoms", such as skin rashes or ulcerated lesions, to refrain from direct physical contact with others.
