Italian energy major ENI with joint venture partners Pakistan Petroleum Limited and Kuwait Foreign Petroleum Exploration Company made the discovery in the Kirthar Fold Belt region 270 kilometres north of Karachi.
"During the production testing gas flowed at 33 million cubic feet per day highlighting an excellent potential for the future for energy needs of the country," the ministry said in a statement.
Officials said that under an early production scheme, gas supply from the new reserve would be possible within three years.
The discovery of new oil and gas reservoirs were "vital" to cope with the prevailing energy shortage in the country, Siddiqui said.
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ENI has been in Pakistan since 2000 and is the country's largest producer, with an average production of 54,800 barrels of oil equivalent per day in 2011.
Pakistan has had an endemic energy crisis for years, characterised by frequent blackouts, which has crippled the economy.
The crisis is blamed on chronic mismanagement and corruption.