The UN Humanitarian Co-ordinator for Somalia, Mark Bowden, says aid is being provided to camps controlled by the Islamist group al-Shabab.
Mr Bowden told the BBC that aid was being given through al-Shabab's drought committees, which run the camps.
Mr Bowden said this could be done as long as the aid was delivered according to humanitarian principles.
He described the situation as so severe that it was vital to scale up aid operations inside Somalia.
The UN's refugee agency estimates that nearly one-and-a-half million Somalis have been forced from their homes but remain in the country.
But until very recently helping them has been very difficult indeed.
Al-Shabab, which rules over large swathes of south and central Somalia, had imposed a ban on foreign aid agencies in its territories two years ago, accusing them of being anti-Muslim.
It lifted the ban 10 days ago as long as groups had "no hidden agenda".'Humanitarian principles'
Mark Bowden said that aid was being delivered to camps run by committees under the supervision of al-Shabab, despite the movement's known allegiance to al-Qaeda.
But he made it clear that this could only proceed as long as humanitarian aid was delivered free of any political connotations.
"The Shabab have, as I understand it, through their drought committees been distributing assistance to vulnerable groups of the population, so they have taken an interest and expressed concern.
"It is of course important to also recognise that the work that we do in these areas will be conducted under humanitarian principles and based on need and without any political association attached to the assistance," said Mr Bowden.