Russia and Canada have said they will ask the UN to rule on their dispute over a resource-rich underwater Arctic mountain range, the Lomonosov Ridge.
Both foreign ministers said after talks they were confident their respective country's claim would be upheld.
Each argued that the ridge was an extension of their country's continental shelf, allowing them to exploit any mineral resources there.
Arctic resources are becoming more accessible due to melting ice.
The five Arctic powers - Russia, the US, Canada, Norway and Denmark - are engaged in a scramble to claim them.
On Wednesday, Russia reached an agreement with Norway on demarcating their Arctic border in the Barents Sea.
Russian Foreign Minister Sergei Lavrov and his Canadian counterpart, Lawrence Cannon, both said after their meeting that the UN should rule on the ridge.
"They should provide a scientific proof that it's an extension of our continental shelf," said Mr Lavrov.
Mr Cannon said for his part: "We are confident that our case will prevail, backed by scientific evidence."
Russia's foreign minister also warned that Nato, of which Canada and the three other Arctic powers are members, should not become involved in settling territorial disputes in the Arctic.
"Our event yesterday in Murmansk [the agreement reached with Norway] shows that these problems are fully resolvable through direct negotiations and according to principles already set out between the relevant Arctic governments," he said.
The Russian Geographical Society is due to host a two-day international forum on the Arctic next week.