South Africa may start exploration for shale gas before elections in April next year, the trade minister said Thursday. \"We need to advance the work on taking a decision on shale gas exploration,\" said trade and industry minister Rob Davies almost a year after lifting a freeze. \"We want to move before the end of this administration.\" The current government\'s term ends next April. Africa\'s largest economy, heavily reliant on coal, is mulling nuclear power and shale gas as new energy sources. The country\'s semi-desert Karoo region potentially has one of the world\'s largest untapped shale fields. The reserves are perhaps even larger than those of its neighbour Mozambique, Davies added, after massive discoveries there in the last three years. \"The gas fields of Mozambique which have just opened have about a hundred trillion cubic metres of gas, and the shale gas deposit -- some of the estimates would suggest that it is multiples of the Mozambican,\" he said in a news conference. \"If this was the case, this could be a very, very significant game changer in terms of the energy situation in South Africa.\" If the estimates are accurate South Africa could have gas equal to 400 years of crude oil imports at the current rate, according to a study released last year and commissioned by Anglo-Dutch energy giant Shell. Authorities last September lifted a freeze on shale gas exploration in the Karoo, sparking a national debate and concerns among environmental activists about the effect on water quality in the arid region. But Davies was reassuring that \"of course we are not going to do this in any kind of irresponsible way.\" Its exploitation could create up to 700,000 jobs in a nation where over one in four people are unemployed.