Iran has revealed the existence of a second uranium enrichment plant. Tehran made the announcement earlier this week in a letter to International Atomic Energy Agency (IAEA) chief Mohammed ElBaradei.The IAEA also confirmed the receipt of the letter from Iran on Monday in which Iran informed the Agency that a new pilot fuel enrichment plant is under construction. Iran has previously acknowledged it has one enrichment plant at Natanz, which IAEA inspectors are monitoring.Reports say the United States, Britain and France are set to accuse Iran of concealing the plant later today. News of the Iranian letter comes days before Iran is due to enter fresh talks over its controversial nuclear programme.