Kano - Gunmen attacked and damaged several mobile phone masts on Wednesday, including those belonging to MTN and Airtel , security sources and one of the companies said.
The attacks occurred in the northern cities of Kano and Maiduguri, where Islamists are waging a low-level insurgency against President Goodluck Jonathan's government.
In Maiduguri, Islamist group Boko Haram's home base in the far northeast, a Reuters reporter saw 10 masts burned to the ground on Wednesday morning and local residents complained there was no mobile telephone reception.
In Kano men on motorbikes destroyed MTN and Airtel mobile phone masts in the early hours of Wednesday, a policeman said, asking not to be named. He said Boko Haram was suspected to be behind the attack.
It was not clear if Boko Haram, which has killed hundreds this year in the largely-Muslim north, was involved. The sect usually attacks government, security or sectarian targets.
Sources close to the sect said Boko Haram members have in the past been concerned they may be traced through mobile phones.
"We confirm that like all the other major telcos, some of MTN's installations in northern Nigeria have been damaged by unknown persons," spokesperson Funmilayo Omogbenigun said.
"All the relevant government security agencies have been informed and we are receiving their full co-operation."
A police spokesperson in Kano and Maiduguri declined to comment, saying investigations were ongoing. Airtel was not immediately available for comment.
Boko Haram's insurgency is aimed at carving out an Islamic state in Nigeria, a country of around 160 million people split roughly equally between Christian and Muslims.