The possibility of an 'all for all' exchange of captives in the south-east of Ukraine will be on the agenda of a meeting of the trilateral Contact Group's sub-groups in Minsk on Tuesday, Organization for Security and Cooperation in Europe (OSCE) Special Representative Heidi Tagliavini told Interfax.

The issue of a possible 'all for all' exchange of captives has always been discussed by the sub-groups, she said.

The OSCE special envoy, however, declined to say whether the situation surrounding two Russian citizens earlier detained in Ukraine would be addressed in Minsk.

The agenda for the June 2 meeting is expected to include the same issues that were raised at the previous meeting in the Belarusian capital, Tagliavini said.