The German airline Lufthansa says it has agreed in principle to sell the loss-making carrier British Midland to International Airlines Group -- which owns British Airways and Iberia.The deal still has to be approved by regulators.If it goes ahead, it would mean IAG would own more than half the take off and landing slots at Heathrow airport. The agreement comes as the company reported a sharp fall in profits for the third quarter of this year.More from our business correspondent, Joe Lynam