A Pakistani official says the country is seeking to sign an international agreement that would allow an exchange of prisoners with the United States. Additional Interior Secretary Saud Mirza said the ministry had requested permission from the Foreign Office to sign the Convention on the Transfer of Sentenced Persons, The Express Tribune reported Wednesday. The decision came after the United States said it was willing to cooperate in a prisoner exchange, Mirza said. Some 64 countries have signed and ratified the convention since the Council of Europe created it in 1985. Pakistan may also sign the Inter-American Convention on Serving Criminal Sentences Abroad, Mirza said. Signing the documents does not guarantee any prisoner exchanges will take place, another ministry official, Usman Ghani Khattak said in a January letter to a U.S. embassy official in Karachi. Pakistan is negotiating the signings of prisoner transfer agreements with 22 countries and trying to sign extradition agreements with 18 countries.