The hard-line Somali armed group al-Shabaab welcomes "Muslim and non-Muslim" foreign aid groups as the region suffers one of its worst droughts in 60 years.
Somalia is close to famine, causing over a 1,000 people a day to leave over the border into Kenya and Ethiopia each day, according to the United Nations.
An estimated 2.8 million people in Somalia are now in need of emergency aid. In the worst-hit areas, one in three children is suffering from malnutrition.
"We have now decided to welcome all Muslim and non-Muslim aid agencies to assist the drought-stricken Somalis in our areas," said Sheikh Ali Mohamud Rage, a spokesman for al-Shabab.
"All aid agencies whose objective is only humanitarian relief are free to operate in our area," Rage said, adding they should first contact al-Shabaab's drought committee.
Al-Shabaab fighters, who some claim are affiliated to al-Qaeda in Yemen, control central and southern parts of the Somalia.
In the past, the group has said food aid created dependency and told aid agencies to pay large registration fees in a bid, some claim, to fund their war efforts.
The latest announcement signifies the scale of the growing humanitarian crisis in the horn of Africa, affecting some 10 million people.
The United States, which regards al-Shabaab as a terrorist group, has already delivered some 19,000 metric tons of food to the UN World Food Programme, much of it already sitting in regional warehouses to be ready for rapid delivery, State Department spokesperson Victoria Nuland said.
The senior UN humanitarian official for Somalia welcomed the news of the lifting of the food aid ban.
"I am happy to cooperate with anybody who can work to alleviate the current crisis to save hundreds of Somali lives," said Mark Bowden, UN humanitarian coordinator for Somalia, who is based in the Kenyan capital, Nairobi.
The UN World Food Programme pulled out of southern Somalia in 2010 because of threats against its staff and demands by al-Shabaab of payments for security.