Food and fuel supplies are reportedly running out in the central Iraqi city of Samarra because of a curfew imposed after an insurgent attack 12 days ago.
Four babies are said to have died in the city's hospital because of a lack of fuel to power their incubators. Two elderly patients have also died.
Residents have called on US and Iraqi troops to end the restrictions and allow humanitarian aid into the city.
But only some aid deliveries have been allowed through after intense searches.
One Iraqi Red Crescent worker from the nearby town of Tikrit said that three of his organisation's trucks had been turned away.
"The humanitarian situation in Samarra is terrible," he said.
The restrictions began on 6 May after a bomb attack killed 12 police officers, including the police chief, Abd al-Jalil al-Dulaimi.
US and Iraqi forces responded by encircling the mainly Sunni Arab city, blocking off entrances with concrete slabs and sand bags.
They then extended the hours of a curfew for the 300,000 residents and imposed very strict restrictions on the movement of people and goods into the city.
The problems caused by dwindling supplies of food and medicine were further exacerbated by the failure of the city's power grid and main water supply, which were both damaged by the bombing.
An Iraqi humanitarian group, Doctors for Iraq, said it was gravely concerned by the situation in Samarra.
"Doctors for Iraq condemns in the strongest terms any activities that prevent civilians from accessing healthcare or humanitarian assistance by all actors engaged in the conflict," it said in a statement on Wednesday.
The group called for an immediate lifting of the access restrictions, which it said amounted to "an act of collective punishment", and for local NGOs and health workers to be allowed into the city as soon as possible.
The governor of Salahuddin Province said he would do what he could to end the crisis as soon as possible.
A spokesman for the US military in Iraq admitted the security measures had "made living very difficult", but said the local authorities had imposed them because of the risk of attacks by insurgents.