Higher world oil prices pushed OPEC member Algeria's trade surplus up to $16.67 billion in the first nine months of 2011 from $13.84 billion in the same period last year, customs data showed, a rise of 20.4 per cent. Exports rose 18.4 per cent to $51.73 billion from $43.7 billion in January-September 2010, while imports were up 17.4 per cent to $35.05 billion versus $29.86 billion in the first nine months of last year, according to customs figures carried on Sunday by the official APS news agency. The value of oil and gas sales abroad, which accounted for 96.9 per cent of total exports, increased 17.9 per cent to $50.14 billion from $42.54 billion.