A Polish scientist held in Iran for months was released and returned home to Poland in December, a foreign ministry spokesman told AFP on Friday.   Maciej Walczak, a researcher at Nicolaus Copernicus University in Torun, central Poland, is "safe and sound and with his family", Lukasz Jasina said in a message to AFP, without elaborating.  Copernicus University spokesman Marcin Czyzniewski said several months ago that Walczak had been held in Iran since September 2021.