Reduced fuel oil output from Russian refineries due to the refinery maintenance season pushed St Petersburg bunker prices higher Monday, bunker sources said.

Low sulfur bunker fuel prices in St. Petersburg rose to a more than six-month high Monday at $483.50/mt. They were last higher on September 24, 2013, when they were at $564.50/mt, data showed.

High sulfur bunker fuel in the Baltic port followed a similar bullish trend with spot prices soaring to a 15-week high set at $400.50/mt. The last time it was higher was December 17 when it was $405.50/mt, data showed.

The bunker fuel price increase was attributed to steady demand and dwindling availability from sellers.

"Refineries have notified that April output will be low," one source said.

"Everyone will be impacted," another source said.

St. Petersburg bunker suppliers said they were focused on a potential shortage of material in April and expecting higher premiums for bunker fuel deliveries for further forward dates.