The two companies have signed a letter of intent to participate in Urals North American Marketing (UNAM), a venture that would transport and market Urals crude to the North American market.

The venture is subject to the signing of definitive agreements and obtaining necessary approvals from the Russian and American governments. The expected start-up time is the third quarter of next year.

"UNAM is intended to help establish the US as a significant long-term marketplace for Urals crude, while providing the US with added diversity of crude oil supply," Marathon said.