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 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.

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'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.

Saudi Arabia’s futuristic city project Neom has announced the departure of long-time CEO Nadhmi Al-Nasr in an abrupt leadership reshuffle.

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.

Neom, Saudi Arabia's ambitious megacity project, is a key part of the kingdom's Vision 2030 scheme. Its CEO stepped down after six years in the role.

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