Rev Phyllis Sortor, an American missionary who was kidnapped in central Nigeria last week, has been freed.

Sortor, 71, a Free Methodist Christian missionary, was safely released to authorities and church leaders on Friday.

"We are deeply grateful to all who prayed for Phyllis' safe return and praise God the family representative was able to secure her release," said David W. Kendall of the Board of Bishops.

Rev Phyllis Sortor, a missionary 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) on Feb. 23.

Nigeria is one of the world's worst countries 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.

"As a matter of sound policy, and to help protect the many, many people who helped secure Phyllis' freedom, we will have no comment concerning the efforts that were undertaken to secure her release," the church said.

Sortor, born to missionary parents, grew up in Mozambique and lived in Seattle. She and her husband lived in Rwanda to do missionary work for six years and the couple went to Nigeria in 2005. "She has also been instrumental in establishing schools in Kogi State for the children of Fulani herdsmen and in instituting grazing projects as one solution to long-term conflicts between Nigerian farmers and Fulani herdsmen," the church said.

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