Gas- and oil-rich Iran has discovered another gas field with reserves of 495 billion cubic metres valued at $133 billion, the oil ministry\'s SHANA news service quoted an oil official as saying on Monday.\"The new gas field has in spot reserves of about 495 billion cubic metres (17.5 trillion cubic feet) valued at $133 billion and is located east of Assalouyeh,\" National Iranian Oil Company (NIOC) managing director Ahmad Qalebani said.Assalouyeh, in the southern province of Bushehr, is the base for developing Iran\'s offshore South Pars field which Tehran shares with Qatar.It holds an estimated 14 trillion cubic metres of gas (500 trillion cubic feet) or eight percent of world gas.The Islamic republic, which has divided South Pars into 28 phases, has proven gas reserves of 33 trillion cubic metres -- the second largest in the world after Russia. Iran consumes almost all of the 600 million cubic metres per day of gas it produces, but hopes to double production and export 250 million cubic metres a day to its neighbours and Europe from 2015 by developing the giant South Pars field.Tehran also announced on Monday an increase of 17 million cubic metres in phase 10 of South Pars, SHANA reported.\"Gas production in phase 10 of South Pars has increased by 17 million cubic metres,\" said Moussa Souri, director of Pars Oil and Gas.But the South Pars development has been delayed amid a lack of investment in a country faced with severe gas needs of its own and because of difficulties in procuring the required technology.Iran\'s vital energy sector is one of the key areas targeted by world powers in sanctions imposed against Tehran for pursuing its controversial nuclear programme. Most Western and European energy firms have withdrawn or put on hold their investments in the country\'s energy sector.Iran is also the second largest producer within Organisation of Petroleum Exporting Countries (OPEC) at 3.7 million barrels per day, and has oil reserves of around 155 billion barrels.