Abdolreza Karbasi, deputy director of the Iranian Department of the Environment, said BP dumped oil waste into the Caspian Sea after exploration campaigns in Azerbaijan. He said the government was considering a lawsuit against BP.
"Last year, southern coasts of Caspian Sea were covered with oily patches and in the last such case, 4 months ago, 25 tons of patches were cleared from Iranian coasts," he told the semiofficial Mehr News Agency.
There was no official reaction from BP regarding the Iranian complaints.
BP was criticized last year by the Azeri government for underperformance at the Azeri-Chirag-Gunashli complex in the Caspian.
Production at ACG during the first half of 2012 was down 12 percent compared to 2011. Azeri President Ilham Aliyev said the situation at the field was "unacceptable."
ACG, operated by BP, is one of the largest oil complexes in the world. BP also manages the Azeri offshore Shah Deniz natural gas field, seen as a major potential source for European energy consumers.