Saudi Arabia's economy is entering a post-oil era in which the kingdom's mega-cities, a number of which are under construction, will provide the country's future growth, Riyadh officials told CNBC on Tuesday.

Fahd al Rasheed, managing director and chief executive of King Abdullah Economic City (KAEC), the world's first publicly listed city, spoke to CNBC at the World Economic Forum (WEF) in Davos, Switzerland, on Tuesday.

"We are now in the business of building cities," he said. "We are talking now about moving to a service economy post oil, and I think the economic driver in the future in Saudi Arabia is going to be these mega-cities."

Al Rasheed said the economy was transforming away from oil.

"The message is that we are entering a post-oil era in which we are diversifying the economy. We had a hard 2016 to 2017 in terms of economic growth, but I think 2018, with the highest ever government budget announced in the kingdom's history, (it should improve)," he said.

"We have seen as a post-oil economy, also lots of growth in areas like the port industry, leisure as well as residential (construction), so we truly believe in the post-oil era and I believe we're going in the right direction there."