Although Boeing executives have declared the issue behind them, Poland's LOT is still pursuing compensation claims over delays caused by the four-month 787 grounding earlier this year.
The airline appears to be using diplomatic channels to keep pressure on the US manufacturer.
In a 7 August meeting, Poland's Treasury Minister Vladimir Karpinski raised the issue of LOT's claim for compensation from Boeing with US Ambassador to Poland Stephen Mull, the ministry says in a statement.
"The US ambassador said that this issue is the subject of talks between the two companies and hope that it will result a proposed solution acceptable to both parties," the statement adds.
The disclosure that LOT is continuing to pursue the claim conflicts with statements by Boeing chief financial officer Greg Smith last month.
Speaking to analysts on a second quarter earnings call, Smith said that the airframer had satisfied all obligations to 787 customers created by the battery-induced grounding and halt of new aircraft deliveries.
Asked if any further compensation demands were pending, Smith replied: "We think they are all behind us now."
The 787 was grounded for four months until Boeing devised an improved battery enclosure to prevent the onboard lithium ion batteries from overheating and generating smoke, toxic fumes or fire.
The grounding order in mid-January caught LOT at a difficult time. The order by the US Federal Aviation Administration was issued as LOT was conducting the inaugural flight of a 787 route between Warsaw, Poland, and Chicago-O'Hare Airport.