Vadym Prystayko, the deputy head of Ukraine's presidential administration, told reporters in Kyiv on July 16 that according to the agreement, the swap must be held within a month, adding that the exact number of people to be swapped had not been established yet.

Prystayko's statement came after Russian ombudswoman Tatyana Moskalkova met with her Ukrainian counterpart, Lyudmyla Denisova, in Kyiv on July 15 and discussed a swap involving the 24 Ukrainian sailors captured near the Kerch Strait last year.

Also on July 15, Ukrainian Foreign Minister Pavlo Klimkin told Current Time that "there will be a development" in the much-anticipated prisoner exchange between the countries, but he declined to provide further details.

A possible prisoner swap was discussed during a phone call between Russian President Vladimir Putin and his Ukrainian counterpart, Volodymyr Zelenskiy, on July 11.

Zelenskiy, who took office in May, raised the issue of handing over the sailors captured by Russia, a statement on the Ukrainian president's website said.

Ukraine has been seeking the release of the sailors and ships since Russian forces attacked and seized them near the Kerch Strait, which links the Black Sea with the Sea of Azov.

Russia illegally annexed Ukraine's Crimean Peninsula in March 2014. Shortly thereafter, Moscow began supporting separatists in eastern Ukraine in a conflict in which more than 13,000 people have been killed since April 2014.

Based on reporting by Interfax, Ukrayinska Pravda, UNN, and TASS