The International Committee of the Red Cross has suspended food distribution to 1.1 million people in Somalia.
The Red Cross stopped the aid after militants from the Islamist group al-Shabaab blocked deliveries in parts of the country.
The rebel group, linked to al-Qaeda, is hostile to Western intervention and outlawed 16 relief agencies in November.
A Somali government minister said the suspension could worsen the humanitarian crisis in a country where 250,000 Somalis already live in famine conditions and a total of 4 million need aid, according to UN figures.
The suspension could involve New Zealand supplies. Last September, the New Zealand government announced a $3 million aid package for Somalia which was in addition to other assistance also amounting to $3 million.
Much of this aid would be delivered to people in Somalia by the Red Cross.
Somalia is the ICRC's second largest humanitarian programme after Afghanistan.
Its efforts to help severely malnourished children, and provide health care and clean water in other parts of Somalia, including Mogadishu, were continuing, it said.