Officers claimed they had "credible intelligence reports" of suicide attacks being planned on the city's transport system, with terrorists also plotting to detonate improvised explosive devices concealed in luggage, bags and cans.
The Islamist Boko Haram sect claimed responsibility for killing 75 people in the bombing of the main bus station at Nyanya, on the outskirt of Abuja, on April 14.
A car bomb at the same spot two weeks later killed 19 and left 80 others injured, while 21 people were killed on June 25 at a crowded Abuja shopping centre in other attacks blamed on the sect.
It urged people to be vigilant, and said that security forces were working to "deal with the threat".
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The Nigerian government has been under intense international pressure since the abduction of 276 girls by Boko Haram from a secondary school in Chibok in the north of the country in April.
Parents and local leaders have accused the military of doing almost nothing to secure the release of the hostages.
Fifty-seven of the girls escaped within days of the night-time raid on the school in Borno state but local officials have said that 219 are still being held.