Indian authorities reported on Monday Asia's first possible monkeypox fatality after a man who recently returned from United Arab Emirates died after testing positive.

Kerala state's health ministry said tests on the 22-year-old "showed that the man had monkeypox".

Three monkeypox-related fatalities have so far been reported outside Africa in an outbreak that the World Health Organization has declared a global health emergency.

The Indian man died in Kerala on July 30 around a week after returning from the UAE and being taken to hospital.

It was unclear however whether monkeypox was the cause of death.

"The youth had no symptoms of monkeypox. He had been admitted to a hospital with symptoms of encephalitis and fatigue," the Indian Express daily quoted Kerala's health minister Veena George as saying on Sunday.

Twenty people identified as being at high risk were being kept under observation, she added, including family members, friends and medical staff who might have come into contact with the victim.

According to the WHO, more than 18,000 monkeypox cases have been detected throughout the world outside Africa since the beginning of May, most of them in Europe.

Spain last week recorded two monkeypox-related deaths and Brazil one.

It is however unclear if monkeypox actually caused the three fatalities, with Spanish authorities as of Sunday still carrying out autopsies and Brazilian authorities saying its deceased patient had other serious conditions.

India has reported at least four cases, with the first recorded on July 15 in another man who returned to Kerala from the UAE.