Nigeria's military on Wednesday banned the use of satellite phones in much of the restive northeast after cutting mobile phone service, further isolating the area after a series of fresh attacks.
The military claimed in announcing the ban that Islamist extremist group Boko Haram had used satellite phones to plan attacks on schools.
The insurgents have attacked two schools in the northeast this week, leaving at least 16 students and two teachers dead.
"Therefore, effective from 19 June 2013, the (military) imposes a ban on the use and sale of Thuraya phones and accessories, including Thuraya recharge cards in Borno state," said a statement from Lieutenant Colonel Sagir Musa.
Thuraya is a popular brand of satellite phones.
"Anyone seen with Thuraya phones, recharge cards and accessories will be arrested," the statement said.
It was unclear whether the ban would also apply to journalists, who have used satellite phones to communicate when visiting the region, where the military launched a sweeping offensive on May 15.
The announcement applied to Borno state, the hardest hit in the region, and it was unclear if it would be extended.
The military has claimed it has pushed out the insurgents with its offensive, but a series of attacks in recent days have raised questions over whether the gains were only temporary.
On Sunday, suspected Boko Haram gunmen opened fire on a secondary school in Damaturu in Yobe state, killing seven students and two teachers.
Two of the attackers were also killed, said the army.
On Monday in Maiduguri, the capital of Borno state, suspected Islamists shot dead nine students as they sat an exam in a private school.
Boko Haram, whose name roughly translates as "Western education is sin," has carried out multiple attacks on schools in northeast Nigeria.
The group has said it is fighting to create an Islamic state in the country's mainly Muslim north.
Violence linked to the insurgency has left some 3,600 people dead since 2009, including killings by the security forces, who have been accused of major abuses.