Security concerns forced the United Nations to pause its aid operations this week in east Mosul, which Iraqi forces recaptured from Islamic State (IS) militants  last month, but they will resume soon, a U.N. humanitarian official said on Wednesday.

"Based on reports of insecurity, the U.N. decided that we would not send missions into eastern parts of Mosul until we reassess security conditions," said Lise Grande, the U.N. Humanitarian Coordinator for Iraq.

"This has now been done and we expect to reengage as soon as possible, hopefully within the next day or so."

A suicide bombing at a restaurant in east Mosul last Friday killed 14 people and wounded 39, the second of its kind in the four-month-old Mosul battle.

The attack fractured a sense of safety and relief that many residents felt after Iraqi forces pushed the Islamist militants out of their neighbourhoods in months of heavy street fighting.

ISwho retreated across the Tigris river to western districts also regularly target civilian areas under government control in the east with mortars and grenades dropped from drones.

Residents in the east have been without electricity for months and have been forced to dig wells for water.

U.S.-backed Iraqi forces are gathering on the perimeter of west Mosul, where hundreds of thousands of people are estimated to be living, for a renewed offensive expected to start in the coming days.