DUBAI/RIYADH (Reuters) -Nadhmi al-Nasr, the long-time chief executive of the $500 billion NEOM mega-project at the heart of Saudi Arabia's drive to diversify away from oil, has departed, NEOM said on Tuesday without giving a reason.

Longtime CEO Nadhmi al-Nasr left Neom, Saudi Arabia’s marquee development, which has been plagued by delays, cost overruns and staff turnover.

Pitched as a mix of ‘Blade Runner’ and ‘Jurassic Park,’ Neom is the world’s biggest construction project. Twenty-one thousand people have died so far to make it happen.

Saudi Arabia announced Tuesday that it was replacing the chief executive of its futuristic mega-city NEOM as scepticism mounts over the Gulf kingdom's most ambitious development projects.

Saudi Arabia replaced the executive that was overseeing its plan to build the $1.5 trillion futuristic development known as Neom, in the latest sign that the project is struggling to deliver on its ambitions.

Following the departure of Nadhmi al-Nasr who had served as the project’s chief executive since 2018, Aiman al-Mudaifer has been appointed as interim CEO, says NEOM in a statement.

Saudi Arabia's ambitious futuristic city plans have been bogged down by delays and changes. The most recent is the departure of its CEO, Nadhmi al-Nasr.

Nasr estimated the total cost of the line alone would be considerably over $2 trillion, which is far more than the country's ability to spend on development. He took the reins in 2018 and pushed staff hard.

The departure of the longtime CEO marks a major shakeup at Neom, which is a showpiece of Riyadh’s economic ambitions.