The regular Oskanian-Mammadyarov meeting will take place in Belgrade April 18 in presence of the OSCE Minsk Group Co-chairs, Yuri Merzlyakov, the OSCE MG Russian Co-chair told PanARMENIAN.Net. He also voiced hope that the mediators will visit the region in late May or early June, before the meeting of the Armenian and Azerbaijani Presidents.