MOGADISHU (AFP) -- Britain's foreign minister Boris Johnson met the new Somali President Mohamed Abdullahi Mohamed in a surprise visit Wednesday to Mogadishu, the scene of frequent attacks by Al-Qaeda-aligned Shabaab Islamists, an airport official said.

"The UK foreign secretary has arrived and he's now meeting with the president," said the official, Mohammed Abdirahman. 

A source close to the Somali presidency confirmed the meeting was taking place in the Villa Somalia presidential palace in central Mogadishu.

Johnson and the Somali leader are set to discuss a severe drought that aid agencies say has left about three million people in crisis.

The World Health Organization (WHO) warned in February that Somalia was at risk of its third famine in 25 years. The last one, in 2011, killed an estimated 260,000 people.

The agency said more than 6.2 million people -- half the population -- needed urgent humanitarian aid, including almost three million who are going hungry.

Somalia declared a "national disaster" over the drought on February 28. The country is among three nations on the verge of famine, along with Yemen and Nigeria. In South Sudan, 100,000 people are already in famine conditions.

Overall, more than 20 million people face starvation in the four countries. 

Johnson's visit to Somalia had not been announced for security reasons.

While there was no official confirmation of where Johnson would head to next, a regional diplomatic source told AFP he might travel to Uganda, Ethiopia and Kenya.