Fuel contamination at Johannesburg\'s main airport has left seven million litres of their stock unfit for usage, sparking fears of flight delays at Africa\'s busiest airport, authorities said Friday. A consortium supplying fuel to the hub detected the contamination late Thursday, reducing stock levels from four to one day\'s supply. A delivery of lower standard,  more volatile fuel contaminated existing stocks. \"The impact of the contamination on the fuel pipeline is such that approximately seven million litres of fuel, which is currently in storage, is unusable, reducing stock levels from four days to 1.6 days,\" said Airports South Africa spokesman Solomon Makgale. Makgale said the airport was contacting airlines to consider the uptake of fuel at other airports to keep operations going. \"These measures are aimed at minimising the impact on airlines, passengers and overall airport operations,\" he said. Makgale said no delays were expected today as the result of the problem. \"We remain hopeful that the fuel suppliers will find a solution as a matter of urgency,\" he said. Despite its southerly location, OR Tambo Airport is a hub for African and local and international destinations. Fuel to the airport is supplied by the Sasolburg-based Natref refinery, some 150 kilometres (90 miles) southeast of Johannesburg. The company is a joint venture between SASOL and TOTAL South Africa.