Four Iraqi aid workers and at least seven civilians have been killed by indiscriminate mortar fire this week during aid distribution in two separate incidents in eastern Mosul.
A UN statement did not assign blame for the attacks, but Islamic State militants retreating from the Iraqi military's offensive in the northern city have repeatedly shelled "liberated" areas, killing or wounding scores of residents fleeing in the opposite direction.
The operation in Mosul, the jihadists' last major stronghold in Iraq, has retaken a quarter of the city but the troops' advance has been slow and punishing. The US-backed campaign launched by a 100,000-strong alliance of local forces on October 17, has become the biggest in Iraq since the 2003 US-led invasion that toppled Saddam Hussein.
Lise Grande, UN humanitarian co-ordinator for Iraq, condemned the attacks as a violation of humanitarian principles.
"People waiting for aid are already vulnerable and need help. They should be protected, not attacked," she said. "All parties to the conflict - all parties - have an obligation to uphold international humanitarian law and ensure that civilians survive and receive the assistance they need."