Qassemi said that the extradition of 283 Iranian inmates is taking place following a visit to Turkmenistan by Iranian President Hassan Rouhani and in line with the implementation of an agreement signed between the two countries.
Iran will also extradite some Turkmen inmates jailed in Iran in exchange for its extradited prisoners.
"Two crew members of an Iranian boat recently seized in Turkmenistan will be also among the Iranian prisoners due to be extradited to Iran," the spokesman said.
President Rouhani arrived in Ashgabat on Tuesday for a two-day visit which then took him to Baku, Azerbaijan.
During President Rouhani's stay in Turkmenistan, 13 cooperation documents were signed between the two countries.