Tawanda Chandiwana (pictured centre) has been kept at a detention centre on the outskirts of the country's capital city, Manila, after being accused of links to a "subversive group". He denies any wrongdoing.
The Zimbabwean national is among three Methodist missionaries - the others are Adam Shaw (pictured right) from Brunswick in Ohio and Miracle Osman (left) from Malawi - who are all currently being denied permission to leave the country.
In a statement the United Methodist Church (UMC) said: "[We] are launching a worldwide campaign to call public attention to the plight of Tawanda and two other missionaries who were in the country fulfilling their commission to show God's love in the world."
Chandiwana and Osman were in the Philippians to complete a 20-month missionary programme which included involvement in peacebuilding, environmental conservation, teaching English, human rights and social work.
Shaw is a former participant on the programme and is now in full-time mission work.
All three individuals were briefly detained and questioned in February will joining a fact-finding investigation into alleged human rights violations near General Santos City in the south of the Philippines.
Chandiwana was later detained while attending a training seminar at the Mindanao Peacebuilding Institute in Davao City.
Thomas Kemper, general secretary of United Methodist Global Ministries, said: "We vigorously protest this treatment of our mission personnel, placed and supervised in collaboration with The United Methodist Church in the Philippines."
The UMC has launched a #LetThemLeave campaign on social media to highlight the case of Chandiwana, Shaw and Osman.
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