The Nigerian statement came as the US State Department on Thursday ordered the departure of diplomats' families and also authorized the departure of non-emergency government employees from Abuja.

"Terrorists may attack with little or no warning," targeting malls, markets, hotels, places of worship, restaurants, bars or schools, the State Department said in its country summary for Nigeria, but did not give further details.

The United States, Britain, Australia and Canada had issued warnings last weekend, although the three latter countries had not ordered any evacuation of staff or their families as of Friday morning.

The government said that Nigerians and foreigners in the country "should continue to be alert but must not panic."

"I can assure all that our military and other security agencies have continued to do everything possible to secure and protect Nigerians and foreigners living in Nigeria," said the Minister of Information and Culture Alhaji Lai Mohammed.

"Terrorists have been hard hit and put on the run," he said during a press conference on Tuesday.

On Thursday, Jabi Lake Mall, a major shopping center in Abuja was temporarily shut down for unspecified security reasons.

Some European embassies and international organisations in Abuja have not updated their risk assessments or travel advisories.

"We have no crisis to manage, we are managing the panic," a senior security manager with an international organisation based in the capital told AFP, asking to remain anonymous.

"We don't know what the motive is (behind the US evacuation). We are taking some precautionary measures/actions, but activities are normal," he added.

Nigerian troops are deployed throughout the West African nation of some 200 million people, fighting against Islamist insurgents and heavily armed criminals.

The last time one of the groups - Boko Haram - attacked the city center was in 2014.

But the Islamic State West Africa Province, linked to the Islamic State group, has claimed several attacks around the FCT in the past six months, including a mass jailbreak in July.