ABUJA, March 12 (Xinhua) -- U. S. Secretary of State Rex Tillerson rounded off his first official trip to five African countries late Monday with a brief meeting with Nigerian leader Muhammadu behind closed doors.

Tillerson spent only a few hours in Nigeria's capital Abuja and flew back to Washington "to deal with urgent work," according to his spokesman.

During his meeting with Buhari, Tillerson discussed issues on security, economy, commercial investments and the 2019 polls with the Nigerian leader.

An official statement by the Nigerian government said another important aspect of Buhari's discussion with Tillerson was the issue of the 110 abducted girls from a college in Nigeria's northeastern town of Dapchi.

Tillerson said the U.S. will assist Nigeria with latest security equipment and intelligence sharing in its efforts toward the safe return of the abducted schoolgirls.

In a press conference here, Tillerson described Nigeria as "a very important country to the U.S.," saying, the U.S will also support opportunities to expand the Nigerian economy,

He said there was the need to increase the volume of trade between the U.S. and Nigeria. Trade between both countries stand at 9 billion U.S. dollars.

Earlier, Tillerson had discussed the threat of terror group Boko Haram in his discussion with President Idriss Deby before departing for Nigeria.

Tillerson's first official Africa visit includes Ethiopia, Djibouti, Kenya, Chad and Nigeria.