Attackers have bombed an Asiacell equipment building near the Iraqi city of Mosul, damaging the mobile phone operator's network and knocking out service in some northern areas, police and officials said on Friday.

The attackers, some of whom wore military uniforms, held guns to the heads of security guards late on Thursday and planted four large explosives in the building, which houses routing and switching equipment, Asiacell chief executive Diar Ahmed said.

"One of them exploded and caused severe damage to the network. The other three were dismantled," Ahmed said.

No one was hurt in the blast, he said.

Ahmed said the centre, located in a normally safe area in a Mosul free trade zone, just 60-70 metres from a police station, serves Nineveh province and parts of neighbouring Dahuk. Work crews hoped to restore service later on Friday, he said.

"It's a partial outage in (Nineveh) province but it's the majority to be honest," he said.

Asiacell is a unit of Qatar Telecom.

Security is one of the key concerns of foreign companies looking to invest in Iraq.

Reuters