David Cameron has been challenge by two global business leaders over the government's approach to immigration and aviation – key areas where ministers have been heavily criticised by industry.

An attempt to use the Olympics to showcase Britain as a business destination was undermined when the heads of Cisco Systems and Emirates airlines questioned him at a Global Investment Conference on Thursday.

The prime minister insisted Britain has an open immigration policy for entrepreneurs and is committed to ensuring London remains an aviation hub, though he added that the government was opposed to building a third runway at Heathrow.

Cameron told Tim Clark, the president of Emirates, that Britain could maintain its status as an aviation hub by providing more officials at passport control at the airport.