"The port is doing health screenings for crew arriving, so there are some vessels who are not calling here," a supplier said.

Sources said the COVID-19 outbreak has led it to slump further.

Jazan is expected to grow Saudi Arabia's refinery capacity grow to around 3.3 million b/d.

"The spread is going back to normal," a supplier said.

"WAF is definitely pulling some high sulfur [gasoil] from all regions...that's likely keeping values strong despite a lack of NWE demand," a trader said.

Values for low sulfur products have been falling back again after spiking in January.

State Department says it's "confident that energy markets will remain stable."