LONDON, June 25 (Reuters) - The spread of mpox in Africa needs to be addressed urgently, the World Health Organization said on Tuesday, as scientists warned separately of the dangers of a new strain spreading in a hard-to-reach part of Democratic Republic of Congo.

"There is a critical need to address the recent surge in mpox cases in Africa," said Rosamund Lewis, the WHO's technical lead for mpox, in a briefing note to journalists.

In a separate briefing, John Claude Udahemuka of the University of Rwanda, who has been working on an outbreak in South Kivu province in DRC, said the strain spreading there was extremely dangerous, with fatality rates of around 5% in adults and 10% in children.

This year, there have been around 7,850 mpox cases reported in DRC, and 384 deaths, according to WHO tallies at the end of May.

Mpox is a viral infection that spreads through close contact, causing flu-like symptoms and pus-filled lesions. Most cases are mild but it can kill.

It has been endemic in parts of Africa for decades, and a milder version of the virus spread globally in 2022, largely through sexual contact, prompting the WHO to declare a public health emergency which has now ended. (Reporting by Jennifer Rigby, additional reporting by Emma Farge; Editing by Susan Fenton)