ROME - Italy's state railway company, Ferrovie dello Stato (FS), signed an agreement with its Iranian counterpart on Tuesday to develop Iran's rail system, Ferrovie said.Foreign firms are keen to exploit opportunities in Iran after the country emerged from years of economic isolation last month when nuclear-related sanctions were lifted.Ferrovie Chief Executive Renato Mazzoncini signed the agreement with Iranian Deputy Transport Minister and railway chief Mohsen Pour Sayed Aghaei during the third mission of Italian businesses to Tehran in recent months.