The head of the African Union, President Macky Sall of Senegal, has expressed grave concern at rising tensions between the Democratic Republic of Congo and Rwanda.
Mr Sall appealed for calm and urged both sides to resolve their dispute through dialogue.
Rwanda says two of its soldiers - Élysée Nkundabagenzi and Ntwari Gad - were being held captive in eastern DR Congo by the Rwandan Hutu FDLR militia, which it says gets support from Kinshasa.
DR Congo earlier suspended flights to Rwanda and summoned Kigali's ambassador - accusing its neighbour of backing M23 rebels, who it now officially designates as terrorists.