The U.S. State Department on Tuesday authorised the departure of non-emergency U.S. government employees and their families from Nigeria due to a heightened risk of terrorist attacks in the country.

The latest travel update comes after the United States and the United Kingdom warned on Sunday of a possible terrorist attack in the capital Abuja, especially aimed at government buildings, places of worship and schools, among other targets.

"The U.S. Embassy Abuja continues to have limited ability to provide emergency assistance to U.S. citizens in Nigeria," the State Department said.

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.

Reuters