SINGAPORE - Brent crude oil's premium to Dubai quotes slipped on Tuesday to its lowest since December as ample sweet oil supply weighed on global markets, according to traders and LSEG data.

The premium for the global sweet oil benchmark against the Middle East sour crude price marker was at 37 cents a barrel, down from 76 cents in the previous session. This is the lowest since Dec. 14, LSEG data shows.

Global physical crude oil markets are weakening because of soft refinery demand and ample supply, traders and analysts have said.

However, the Middle East market is still supported by voluntary supply cuts by the region's producers to meet OPEC+ commitments.

OPEC+ is a producers' group consisting of the Organization of the Petroleum Exporting Countries and their allies including Russia.

A narrower Brent-Dubai spread could encourage some Asian refiners to buy more crude from the Atlantic Basin while making Middle East supply comparatively more costly, traders said.

(Reporting by Florence Tan Editing by David Goodman, Kirsten Donovan)