Al-Qaida-linked militants in Somalia have vowed to keep most international aid workers out of the country despite a worsening famine.

This week, the United Nations declared a famine in southern Somalia's Bakool and Lower Shabelle regions and said nearly half of Somalia's population needs urgent aid. On Friday, the World Health Organization said five more regions in southern Somalia are on the brink of famine.

But the militant group, al-Shabab, says the U.N. declaration of a famine is simply “propaganda.”

Al-Shabab spokesman Sheikh Ali Mohamoud Rage on Thursday accused the U.N. of exaggerating the crisis for political reasons. He said al-Shabab will allow increased aid only from foreign agencies currently working in its strongholds, not from organizations it has banned. But he did not specify which organizations.

On Friday, Canada said it would increase by $50 million its humanitarian aid to East Africa. It is not clear if the Canadian relief agencies are among those banned by al-Shabab.

Meanwhile, the U.N. refugee agency said the death rate of starving Somalis reaching refugees camps in Ethiopia and Kenya is climbing and the exodus of Somalis is continuing at a high rate.

Relief groups are searching for ways to deliver life-saving aid inside the country to save lives and prevent the mass exodus of Somalis to overcrowded camps in neighboring countries.

Relief groups say personnel must keep a low profile to avoid being targeted by the militants, whose members sometimes demand payments and seize deliveries.

The U.N. estimates that tens of thousands of Somalis have already died of malnutrition. It warns a rapid increase in aid is needed to prevent the widespread loss of life.

Overall, the Horn of Africa is experiencing the worst drought in six decades. The U.N. has said more than 11 million people are in need of food aid.