The information was reportedly announced in a letter sent to him.
However, government officials said the letter contained no details about any specific location of the second plant, or any other information that government agencies across the world would be interested in, The Daily Express reports.
Iran had, earlier, acknowledged having only one such uranium enrichment plant, following which the UN Security Council had placed it under three sets of sanctions for refusing to freeze its enrichment programme that can produce both nuclear fuel and warhead material.
The disclosure could throw the October 1 talks between Iran and six world powers, including the five permanent UN Security Council members and Germany, into a big mess.
According to reports, during the meeting between the seven countries, UN Security Council members and Germany would be pressurizing Iran to scale back on its enrichment activities.