At least four Nigerian newspapers said soldiers have stopped and seized copies of its editions over security concerns, with one paper likening the raids to censorship during the country's military rule.
The military confirmed the searches, the AFP news agency reported, but officers denied that the moves were designed to muzzle critics, even though at least two of the newspapers had published articles denouncing the army in recent days.
Four dailies - The Nation, the Daily Trust, the Leadership and Punch - all said they were affected, while The Nation said soldiers stormed one of its circulation offices.
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The Daily Trust said the military set up roadblocks around its offices in the capital Abuja and the northern city of Kano, as they confiscated its newspaper editions and arrested delivery truck drivers.
"One of the military men told us that they were acting on order from above as there were allegations that newspaper circulation vehicles were being used to smuggle arms and ammunition," one of The Nation's distribution managers said.
The early morning raids did not appear to target specific editions and the copies seized were destined for all parts of the country, the newspapers said online.
Defence spokesman Chris Olukolade said the search "followed intelligence report[s] indicating movement of materials with grave security implications across the country using the channel of newsprint-related consignments".
Nigeria's military has been under sustained pressure, including in the media, over its response to attacks by the armed group Boko Haram, which abducted more than 200 schoolgirls in April.
'Routine security action'
Attacks by the group, which have claimed thousands of lives since it began five years ago, have increased, with the military apparently powerless to prevent the violence.
But Olukolade rejected reports the army was trying to stifle free speech, calling the media "an indispensable partner in the ongoing counter-insurgency operation and the overall advancement of our country's democratic credentials".
"As such, the military will not deliberately and without cause, infringe on the freedom of the press," he added, calling the search a "routine security action".
Sue Valentine, Africa programme coordinator for the New York-based Committee to Protect Journalists (CPJ) warned that "denying Nigerians access to news and information sows the seeds of rumours and distrust".
"While we recognise that Nigeria faces security threats, these can never effectively be addressed by media blackouts or persecution of journalists," she said.