Michael Laubsch, who works for the 'Eurasian Transition Group', an NGO, says that Turkmenistan is key for the Nabucco pipeline project, which is designed to bring gas to Europe from sources other than Russia.
Unless the political situation in Iran changes, Nabucco must focus on Turkmen gas – otherwise the project does not make sense economically, he argues.
Describing Turkmenistan as a "dictatorship", Laubsch argues that the EU cannot make any plans until the country is transparent about its gas resources.
Western politicians' arguments that an intensified economic relationship would also mean a change of political culture in countries such as Turkmenistan are more or less hypocritical, he said.
"The EU should demand independent and objective test drillings and publication of the results before investing a huge amount of assets," Laubsch insisted.
He argued that Turkmenistan has a tradition of "pendulum" policies between Russia and the EU, which Moscow has always won, resulting in benefits from the Russians for Turkmenistan.
Laubsch warned that China is in fact Russia's real rival in Turkmenistan. "I would predict that during the next decade the Chinese influence in Central Asia will increase, while the Russian influence will decrease and the EU concept can be ignored because of a lack of success," he said.
The expert was also sceptical about plans for a section of Nabucco to cross the Caspian seabed, which is considered to be both an internal sea and the largest lake on Earth.
Oil reserves in the Caspian basin are estimated to be worth several trillion dollars, and negotiations over the demarcation of the Caspian Sea have been ongoing for nearly a decade among the states bordering the Caspian - Azerbaijan, Russia, Kazakhstan, Turkmenistan and Iran.
In this context, Laubsch said that the legal status of the Caspian Sea, combined with its estimated energy resources, constitutes a risk to the region's security and stability.
"Unless all Caspian countries solve this problem, Western investments in the region will be at risk," he warned.