In a statement on its website, the company said it never hid its sponsorship of the event from the participants, including the members of the Congress. 

"SOCAR’s logo and name were present prominently at the event,” the company said, adding it was up to the trip’s public sponsors to let the public know of SOCAR’s financing of the conference.

"We are disappointed that the compliance procedures were not followed correctly by the trip’s sponsors,” it said. "SOCAR would be happy to work to address the situation. We also look forward to sponsoring future events involving (US) lawmakers.”