A Christian cleric on Thursday criticised Chancellor Angela Merkelfor kowtowing to Egyptian President Abdel Fattah al-Sisi and downplaying human rights concerns as she headed to north Africa to expand trade and investment ties.

Joachim Schroedel, a German cleric who has worked in Egypt for more than two decades, expressed anger at Merkel's assertion that Egyptian Copts were in a "very good situation" and her description of Egypt as a stabilising force in the region.

Egypt's Christian minority have been targeted in a series of attacks by Islamist militants, most recently the bombing of Cairo's largest Coptic cathedral in December that killed 28 people.

"What does the chancellor want to accomplish with such genuflection," he told the mass-circulation Bild newspaper.

Merkel held talks with Sisi in Egypt before visiting Tunisia as part of a broader push to boost German investment in Africa, slow the flow of migrants into Europe and increase intelligence-sharing to combat Islamic terrorism.

Those issues took on new urgency after a failed Tunisian asylum seeker killed a dozen people in an attack on a Berlin Christmas market in December.

Meanwhile, Germany has made strengthening economic development in Africa a priority of its presidency of the G20 group of industrialised countries this year.

Merkel, who is campaigning to win a fourth term in office in national elections in September, will however need to balance public concerns about alleged human rights abuses in Egypt and across the region.

Amnesty International urged Merkel to press Sisi to revoke restrictions on human rights activists.

"Civil society, media and the political opposition are suffering increasingly under state repression, which often takes place under the pretext of the so-called fight against terrorism," said Rene Wildangel, an Egypt expert at the advocacy group