An American woman working as a Christian missionary in Nigeria has been kidnapped.

Rev Phyllis Sortor, a misisonary with the Free Methodist Church, was taken away by masked gunmen in the central Nigerian town of Emiworo, Kogi state, at around 10am (9am GMT) according to Kogi state police spokesman Sola Collins Adebayo, quoted by AFP.

"Early this morning we received a report that Rev Phyllis Sortor, our missionary in Nigeria, was abducted from the Hope Academy compound in Emiworo, Kogi State, Nigeria by several persons," the Free Methodist Church said on its website.

In the same statement, Bishop David Kendall urged prayer.

"The US Embassy has been notified, and the State Department and the FBI are working with local authorities to find and rescue her. We are calling on the US church to join together in prayer for Phyllis' safety and speedy release," he said.

Nigeria is one of the world's worst country's for kidnapping, a major criminal enterprise that makes millions of dollars a year.

Criminal gangs have kidnapped scores of expatriates in southern and central Nigeria over the years. Central Kogi state has also had low level activity by Islamist militants linked to insurgent group Boko Haram, security sources say.

A US State Department official said authorities had heard the reports but could not make further comments in the interest of privacy.

According to the Free Methodist World Missions website, Sortor works through leadership development and International Child Care Ministries (ICCM). "She is financial administrator of Hope Academy and the Hope extension school at Ikot Ntuk," the site reads. "A special friendship with a clan of nomadic Fulani has given Phyllis the opportunity to open additional schools for Fulani children and their parents. Phyllis teaches at the modular Bible school and Wesley Evangelical School of Theology (WEST) and supports Community Health Evangelism and area women's literacy."

In her latest newsletter, dated January 20, 2015, Sortor writes of the 'joy' of a new school opening in Enugu. "We have worked long and hard on this school, and are so thrilled that yesterday, January 19th, 2015, we were able to open our doors for the first time!" she writes.

"We began with 82 children, 58 of whom are Muslim, Fulani kids from one near-by camp! (There is a second camp preparing to send their children as well!) We have two excellent, Hausa-speaking teachers for these Fulani kids! The Fulani parents are wonderfully cooperative - sending food and water with their kids, organizing a Parent-Teacher Association - giving us Fulani security guards for the school! We have 6 teachers altogether; a tutor/chaplain, bursar, driver and 'mother's helper'. All are wonderful Christian people who I know, with God's help, will make this school great!"

Additional reporting by Reuters.