Azerbaijan's top energy official has urged further scrutiny of the international consortium developing the Caspian Sea nation's main oil field amid mounting irritation at a slump in output.

According to The Associated Press, Industry and Energy Minister Natiq Aliyev said Monday, Oct 15 that the drop-off in production over recent years at the Azeri-Chirag-Guneshli project was "abnormal."

President Ilham Aliyev said last week that errors by AIOC, the field development consortium led by BP, had cost the country $8 billion in lost revenue.

BP Azerbaijan says it's working with state oil company SOCAR to address production issues.

Natiq Aliyev insisted criticism should not be interpreted as a signal of worsening conditions for international investors in the ex-Soviet nation.

BP controls a 35.8 percent stake in the project, while SOCAR has 11.6 percent and Chevron has 11.3 percent.