U.N. spokesman in Myanmar Aye Win said humanitarian deliveries in areas controlled by the Kachin Independence Army are restricted. The Kachin movement hasn't given full permission to aid workers to travel in the area.
"We now can only travel to the places where we are allowed to go," he told Thai newspaper The Irrawaddy.
The Myanmar government agreed to facilitate aid delivery to Kachin state early this year. Aid workers and Kachin rebels said aid would increase once progress on peace is made in the area.
Myanmar President Thein Sein was awarded by the International Crisis Group for political reforms that began with general elections in 2010. The European Union this week eased sanctions on Myanmar in response to those reforms.
The president imposed martial law over parts of Myanmar last month following clashes between minority Muslims and Buddhists. Similar conflicts erupted last year in other parts of the country, including Kachin and Rakhine.
Rights groups were critical of the ICG and the EU for lauding Myanmar. Easing sanctions removed the pressure that brought about political reforms, rights groups said.