Six South African airlines are being investigated for allegedly colluding to hike fares for local flights during the football World Cup in June.The presidency said it had received calls from the public complaining that fares had become "drastically high".South African Airways has agreed to provide the Competition Commission with evidence against the other airlines.Fifa recently said fewer foreign fans than expected would go to the World Cup - partly due to a lack of flights.Many fans are likely to fly between different World Cup venues which are spread around South Africa.The airlines being investigated are: British Airways/Comair, South African Airways (SAA), 1Time, SA Airlink, SA Express and Mango.Except for SAA, the other airlines have denied the allegations but said they would co-operate with the commission.Extra flightsThe 2010 co-ordinating unit in the president's office asked the Competition Commission to investigate the complaints."We hope the commission will resolve this matter timeously to ensure that this does not prove detrimental to the tournament and to tourist attraction," said Zukile Nomvete, head of the unit, report South Africa's Times newspaper.SAA has already provided e-mail correspondence between the airlines, which allegedly backs up the charges of price-fixing.On Wednesday, world football authority Fifa said it was now expecting around 450,000 foreign fans to travel to South Africa - down from initial estimates of one million.It said they were partly put off by the cost of flying to South Africa - a separate issue to the one now being investigated.Fifa secretary-general Jerome Valcke said the organization would now work with local football associations to create extra flights and packages for fans to attend the World Cup.In 2006, SAA was fined 55m rand ($7m; £4.5m at current prices) after being found guilty of price-fixing with German carrier Lufthansa. The airline was also fined on two-charges of anti-competitive behaviour.Source: BBC