Diplomats' families to leave Nigeria's capital US orders

State Department orders release of families of US embassy staff in Nigerian capital over fears of a terrorist attack.

It has reiterated a warning to Americans not to travel to any part of the country.

Two days after the announcement, the department said it would allow non-essential workers to leave voluntarily.

For Nigeria, a  revised travel advisoy said, "The Department ordered the departure of family members of US government employees from Abuja due to the increased risk of terrorist attacks there."

Nigeria has been battling an Islamic insurgency for a long time and attacks are rare in Abuja.

In 2011, some members of the Boko Haram group bombed a United Nations building, killing 21 people.

Since Sunday, the US Embassy in Abuja has been warning about the "increasing risk of terrorist attacks".

According to them, "The attack included places of worship, government buildings and other public places.