United Nations Secretary-General Antonio Guterres has arrived in Somalia on an emergency visit aimed at drumming up support for an effort to avert a famine that could affect 6.2 million people.

Guterres said the world "must act now" after he arrived in the capital Mogadishu.

Just arrived in Somalia on emergency visit to focus on famine & cholera. People are dying. The world must act now to stop this. — António Guterres (@antonioguterres) March 7, 2017

Somalia's newly-elected President Mohamed Abdullahi Mohamed met with the UN chief on Tuesday.

"My first priority is to address this drought crisis and my main priority is to make an appeal to the international community to help us," Mohamed said.

The World Health Organization (WHO) has warned there are just two months left to avert what would be Somalia's third famine in 25 years. The last one, in 2011, killed nearly 260,000 people.

The situation has become "significantly worse in the last six months," the UN said on Monday.

READ: EXPLAINER - What is a famine?

Last week, the government declared a national disaster as the drought continued to ravage the country.

According to the WHO, more than 363,000 acutely malnourished children and 70,000 severely malnourished children are in need of urgent, life-saving support.

The Horn of Africa nation is one of three countries - along with Yemen and Nigeria - that aid agencies say are on the verge of famine. A famine was declared in South Sudan last month.