Nigeria urges residents to stay calm and take "necessary precautions," with police ordering a counterterrorism exercise in Abuja, where US and UK warn of possible terror attacks.
According to international media, Nigerians have expressed worry over security alerts issued by the US and British embassies that warned of a heightened risk of terrorist attacks, especially in the capital Abuja aimed at government buildings, places of worship and schools, among other targets.
On Tuesday, the US authorised the departure of diplomats from the Nigerian capital Abuja, stepping up precautions over what it said was the threat of attacks.
"The US Embassy Abuja continues to have limited ability to provide emergency assistance to US citizens in Nigeria," the State Department said.
The British embassy has also warned their nationals in the capital to be vigilant.
"You should avoid places where crowds gather, including political meetings, religious gatherings and places of worship, markets, shopping malls, hotels, bars, restaurants, transport hubs (including train networks) and camps for displaced people," said the UK embassy’s advisory.
Nigeria's Department of State Services said the United States had previously issued similar warnings and urged citizens to remain alert.
Insecurity, which is rife across most Nigerian states, is a major issue among voters who will choose a new president next February.