Abuja, Nigeria - Nigerian police have accused eight foreigners of being Islamist fundamentalists, trying to incite violence through their sermons.
The men, believed to be six Gambians and two Indians, were arrested at a mosque near the capital Abuja a week ago, police have revealed.
Members of the public had tipped the police off about the men.
Nigeria has never suffered an attack by al-Qaeda, but western diplomats have warned Nigeria could be vulnerable.
"The men were speaking with the aim of causing trouble and mayhem," police spokesman Yemi Ajayi said.
None of the men have been charged with any offence and investigations are still going on.
Local media reported police sources saying the men were from Afghanistan and had false passports, but the police could not confirm that to the BBC.
Violence
In November, hundreds of people were killed in the central city of Jos in violence between Muslim and Christian groups.
The police said the men arrived in the country shortly after the violence in Jos.
BBC correspondents say political rivalries and contested claims to natural resources are responsible for stirring up tension between ethnic and religious groups in Nigeria.
When violence breaks out, "foreign influences" are often blamed by the authorities.
But the killings followed local elections which opposition parties claimed were rigged.
'Vulnerable'
Last year US and UK diplomatic missions issued warnings of possible attacks by Islamist militants on the capital and oil infrastructure in the southern Niger Delta.
They are nervous that Nigeria's porous borders and widespread corruption could make it easy for militant cells to hide.
Five men were last year arrested and accused of being al-Qaeda operatives, but their lawyers said the evidence against them is weak.
Another man is currently on bail, facing charges he was al-Qaeda's link between Nigeria and Pakistan.
His lawyers say he was tortured into making a confession.