Nigeria on Thursday said it has discovered 22 Boko Haram members among citizens deported from Cameroon who were put at the Internally Displaced Persons (IDPs) camp in northeast city of Mubi in Adamawa.

The members were identified with a peculiar mark on their backs among the 12,000 deported from Cameroon, Muhammad Sani Sidi, the Director-General of National Emergency Management Agency (NEMA) said in Abuja.

He added that 90 percent of the deported persons were from restive northeast state of Borno.

"We arrested 22 of them yesterday (Wednesday) who were actually planning an attack, they were identified with a mark inscribed on their backs with hot iron in form of tattoos," he added.

The mark on their backs indicates that they are ready to die, Sidi said.

He said there were 23 residential camps in Borno and that the state government planned to open more as the number of displaced persons was increasing.

Boko Haram insurgents have also intensified suicide bombings and other armed assaults at different locations in the beleaguered northeastern states of Borno, Yobe and Adamawa.

The group has also launched attacks in such neighboring countries as Cameroon, Chad and Niger.