The death of senior Islamic State figure Haji Imam has been hailed by Foreign Secretary Philip Hammond as bringing the defeat of the militant group "another step closer".
US forces killed the group's finance minister this week as part of efforts to target the hierarchy of IS, also known as Isil and Daesh.
"We are systematically eliminating Isil's cabinet," US defence secretary Ash Carter told a Pentagon press conference.
"Indeed, the US military killed several key Isil terrorists this week, including, we believe, Haji Imam who was an Isil senior leader serving as a finance minister and who also was responsible for some external affairs and plots."
He added: "Leaders can be replaced. However, these leaders have been around for a long time. They are senior, they are experienced."
Mr Carter did not say whether the IS finance leader was killed in Syria or Iraq.
Foreign Secretary Mr Hammond said on Twitter: "Another step closer to defeating #Daesh with the death of Haji Imam. #CoalitionProgress continues."
The US military has killed numerous Islamic State leaders in recent months. Earlier this month the Pentagon said it killed Omar al-Shishani, described as the Islamic State's "minister of war", in an air strike in Syria.