Sir Andrew Witty, the chief executive of pharmaceutical giant GlaxoSmithKline, has called for more transparency over drug pricing and revealed the pound's decline over the last six months had delivered a major boost to his company.

Speaking at the World Economic Forum in Davos, Switzerland, Witty said the pharmaceutical industry had to act together to ensure drug pricing was as easy to understand as possible.

Last week, US President-elect Donald Trump lambasted pharmaceutical firms for producing their products outside the US and singled out the "disastrous" pricing issues that plagued the sector.

They're leaving left and right," Trump said at his first formal press conference since being elected. "They supply our drugs, but they don't make them here.

"We're the largest buyer of drugs in the world, and yet we don't bid properly. And were going to start bidding, and we're going to save billions of dollars over a period of time."

Witty argued the debate over drug prices in the US was a long-standing issue rather than a recent one, and stressed the industry had a "sincere and intense" focus on price transparency and on innovation.

"We need to work together with everybody in the health system to get a more transparent system so that people really understand what the costs of these medicines are," he said.

"We need to be working together to get to a sustainable position because what everybody wants is innovation.

"To have innovation we have to make sure there is reward, but that reward needs to be affordable."

GSK, the Britain's largest drug maker, has been among the UK firms to have benefited from the pound's sharp depreciation following the Brexit referendum in June last year. Witty said sterling's decline was unlikely to be detrimental to innovation, although he warned the firm could face regulatory concerns.

"The only issue of concern is the future of European regulations within the [forthcoming] changes in the structure of Europe," he explained.

"We are a significant international player and while we have a big presence in Britain, the pound has been a significant benefit for us."

Witty, who spoke alongside Microsoft founder Bill Gates, Jeremy Farrar, the director of the Wellcome Trust and former Norwegian Prime Minister Erna Solberg, also added GSK was among the companies backing an effort aiming to develop vaccines that could be deployed quickly.

He highlighted deploying the drugs swiftly was of a paramount importance to contain outbreaks before they triggered a global crisis.

"When you look at the different pandemic threats over the last 10 or 12 years, the global response has been challenged each time," he said. "The goal would be to have more, let's say, phase II completed vaccines ready against the risk of potential pathogens, so when one of those comes along, we'll have much better readiness."