Johannesburg - Unions and employers are in their mid-year bargaining session known as strike season, with many labour groups seeking a wage increase more than double South Africa's 4.6% inflation rate. Central bank and Treasury officials have said wage hikes well above inflation present a long-term risk to the economy by making labour more expensive, swelling state spending and forcing up prices. The wage deals also hurt the long-term viability of the economy by driving up labour costs for a workforce that is already more expensive and less efficient than those in many of its emerging economy rivals. In the latest move, scores of filling stations were out of petrol on Thursday due to strikes, raising concerns about a fuel shortage that could hit the economy. Tens of thousands of workers in the sector began walking off the job on Monday, delaying fuel deliveries and sparking panic buying at service stations in Gauteng.The following is a look at other major labour conflicts in South Africa: The Chemical, Energy, Paper, Printing, Wood and Allied Workers Union, which represents over 70 000 workers, said last week it is seeking 11% to 13% wage increases for 2011/12.More than 1 million public sector employees who walked off the job for several weeks last year have said wage talks this year are close to breakdown. The workers received a 7.5% wage hike last year. The wage bill for state employees has increasingly strained the budget. In 2009/10, 47% of tax revenue went to their wages and benefits. Workers at power utility Eskom have begun their demands with calls for 16% to 20% wage hikes. Eskom, struggling to pay for new power plants after an electricity crunch in 2008 that forced miners and smelters to shut, gave workers a 9% raise last year. The powerful National Union of Mineworkers (Num), with more than a quarter of a million members, is seeking a 14% rise in wages from gold and coal miners. Mining firms have offered 4% increases. The Num is also demanding a 14% increase from Impala Platinum, the second-largest producer of the precious metal, and from largest producer Anglo American Platinum.Steel and engineering firms have reached a wage deal with the National Union of Metalworkers of South Africa (Numsa) to end a two-week strike.Union Solidarity is seeking 13% pay increases for its workers in the petroleum sector while employers - including Sasol, PetroSA and Engen - have offered 6%.Freight logistics group Transnet reached a deal with trade unions in May for an 8.5% rise in wages. A strike at Transnet last year cost the economy about $1bn in lost production and sales.