Sani Usman, army spokesman, said this in a statement on Tuesday.
He said two policemen and 24 civilians were also arrested for the alleged offence.
Usman did not disclose their identities, but he said more suspects would be arrested.
“Please be informed [that] the ongoing investigation on suspected Boko Haram terrorists collaborators and saboteurs in the fight against terrorism and insurgency has led to the arrest of nine more persons over the last 24 hours, thus bringing the number to 30,” he said.
“This comprises two officers, two soldiers, two policemen and 24 civilians. Many more suspects would be arrested and prosecuted based on evidence against them and level of culpability.”