"We removed the point of contention on the matter of a prisoner exchange. We're going to exchange 150 for 225," the separatist leader said.
Zakharchenko did not indicate, however, which side would be giving which quantity.
At an earlier press conference Wednesday, an advisor to the head of Ukraine's security service, Markiyan Lubkivsky, said the Ukrainian government was prepared to return 225 individuals to the separatist territory.
Swapping prisoners is a part of the Minsk protocol, which is aimed at ending the conflict between the government and pro-Russian separatists in east Ukraine.
The conflict, which began in April, has claimed over 4,700 lives, according to the UN.