The hardline Muslim armed group battling Somalia's weak government has lifted a ban on humanitarian agencies supplying food aid to millions of citizens amid one of the region's worst droughts in 60 years, a spokesman for the fighters said on Wednesday.

"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.

Somalia is experiencing pre-famine conditions, driving more than 1,000 people over the border into Kenya and Ethiopia each day, according to the United Nations.

"All aid agencies whose objective is only humanitarian relief are free to operate in our area," Rage said, adding they should first contact al-Shabab's drought committee.

Al-Shabab, which is connected to al-Qaeda networks in Africa and the Gulf, controls the majority of Somalia, including around half of the capital, Mogadishu, where Rage gave his press conference on Wednesday.

In the past, they have said food aid creates dependency, but they have also used aid for themselves and charged foreign organisations high fees to operate.

One fourth of Somali population displaced

The United Nations says 2.8 million people in Somalia need emergency aid and that around one fourth of the entire population has been displaced - either internally or as refugees leaving the country - as a result of famine and a long-running civil war. In the worst-hit areas, one in three children is suffering from malnutrition.

Local analysts in Somalia said al-Shabab lifted the ban on foreign aid organisations to generate money to fund their war effort, by charging those groups a registration fee.

Since al-Shabab banned foreign aid, an increasing number of Somalis have been fleeing into government-controlled territory seeking assistance, to al-Shabab's apparent dismay.

On Tuesday, al-Shabab soldiers blocked two trucks carrying people from southern Somalia to Mogadishu, in the hope of finding food and water.

"Al-Shabab fighters said they would not allow people to flee to Mogadishu, which is ruled by infidels," shopkeeper Ali Hussein told the Reuters news agency by phone on Wednesday from Afgoye, 40km (25 miles) outside the Somali capital. "Al-Shabab said it would open kitchens for them."

UN welcomes ban lifting

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, the UN humanitarian coordinator for Somalia, who is based in the Kenyan capital, Nairobi.

The UN World Food Programme would not comment. It pulled out of southern Somalia in 2010 because of threats against its staff and al-Shabab's demands for payments in order to provide security.

The world's biggest food agency has also faced challenges from donors after a local WFP contractor was exposed last March as a Somali businessman with links to al-Shabab.

The lifting of the ban likely won't immediately help the millions of Somalis continue to suffer in their drought-plagued country.

"We don't have anything to eat," said Sainab Yusuf Mohamed, whose child died as they were trekking across the desert in search of help.

"As we were burying his body, my second child died," she said by telephone from Bardhere District in southwest Somalia.