Dakar, May 31 : The Chairperson of the African Union (AU) has called for "calm and dialogue" between Rwanda and Congo, expressing serious concern over the rising tension between the two neighbours. "I call for calm and dialogue between the two countries, and for the peaceful resolution of the crisis with the support of regional mechanisms and the African Union," Senegalese President and current AU chief Macky Sall said on Monday on social media. "I am seriously concerned by the rising tension between Rwanda and Congo," Sall added on Twitter. Congo accuses Rwanda of supporting March 23 Movement (M23) rebels in North Kivu, a province in eastern Congo, an accusation denied by Kigali. Over the past few days, fighting has raged between the Congolese army and M23 rebels in North Kivu, forcing thousands of civilians to flee their homes, Xinhua news agency reported. On Saturday, the Rwanda Defence Force (RDF) urged for the release of two Rwandan soldiers being held by FDLR rebels in Congo. In a statement, the RDF said the two soldiers were kidnapped while on patrol and accused Congolese armed forces, together with the Democratic Forces for the Liberation of Rwanda (FDLR), of launching an attack along the border. /IANS