The story is similar in Asia, the second largest market for US-sourced cargoes, where the price of delivered gas has also declined significantly.

Concerns loom over an expected longer-term supply shortfall and the growing pressure to address climate change.

Clean and dirty tanker freight are expected to be strongly supported in 2020.

The strong economic incentive has lured many to low-viscosity distillate fuels.

Most sellers were opting for delivered rather than ex-wharf sales due to stronger delivered margins.

"It is impossible for Singapore to get 6 million mt a month of LSFO," a fuel oil trader said.

Some 11 years after the International Maritime Organization committed to a 0.5% sulfur limit for marine fuels and three years after it confirmed a 2020 start date, the deadline for the IMO's lower sulfur cap has arrived.