Europe aims to break the Russian grip on the regional energy sector through a package of projects dubbed the Southern Corridor, which includes the much-lauded Nabucco pipeline.
Vagif Aliyev, an investment official at the State Oil Co. of Azerbaijan, was quoted by the Azeri Press Agency as saying there were concerns about Nabucco.
"There are unresolved issues with the Nabucco project," he said.
He declined to specify which issues he had with the project, though his country might not be able to fill Nabucco completely with gas from its giant Shah Deniz 2 field in the Caspian Sea.
Nabucco has faced economic obstacles and hasn't received firm commitments from natural gas suppliers to allay critics.
Azerbaijan is weighing proposals for resources from its Shah Deniz 2 gas field from pipeline groups involved in the Southern Corridor.
Of those, the Nabucco pipeline would be the most ambitious and carry the largest volume of natural gas at an estimated 1 trillion cubic feet per year. Shah Deniz couldn't support Nabucco by itself, however.