Nigeria's police chief has ordered 24-hour surveillance of all telecommunication facilities, after attacks that destroyed mobile phone towers in the country's north.

The Islamist militant group known as Boko Haram claimed responsibility for the attacks Thursday, saying telecom companies are helping security agents track and arrest the group's members, apparently through their cellphones.

In a statement, the group said it “will continue waging these attacks until they (the companies) stop helping the government in fighting us.”

In response, Police Inspector-General Mohammed Abubakar has ordered state and local commanders to form special units to protect telecom installations. He asked the public to tell police if they see any suspicious activity.

Boko Haram on Thursday also threatened Voice of America, charging that VOA “has undertaken the task of harming our religion.” VOA's Hausa language service broadcasts to Nigeria.

This is the second time the group has threatened journalists. In May, a YouTube video attributed to Boko Haram contained threats against VOA and other international news organizations.

Human Rights Watch says Boko Haram is responsible for more than 1,400 deaths over the past three years. Most of the bombings and shootings attributed to the group took place in northern Nigeria.

The group is believed to have several factions, which has confused government efforts to end the violence, either through security measures or negotiations.

The statement issued Thursday said the group has no purpose other than to ensure the establishment of an Islamic state.