* Gas system oversupplied by 11.3 mcm
* Three new LNG tanker deliveries due in next two weeks
LONDON, Feb 17 (Reuters) - British prompt gas prices eased on Tuesday on an oversupplied system and expectations of supply from liquefied natural gas (LNG) tankers due to arrive in the next few weeks.
Prices for within-day delivery were trading at 50.85 pence per therm at 0902 GMT, down 0.55 pence since their last settlement.
Prices for delivery on Wednesday were 0.45 pence lower at 51.00 pence per therm.
Gas flows from Norway via the Langeled pipeline, Britain's main subsea gas import route, were at full capacity at around 70 mcm/day on Tuesday morning, helping to offset low supplies from the Netherlands.
Gas supply from the Netherlands have been low since last week. The Dutch government said earlier this month that production from its giant Groningen gasfield would be capped at 16.5 billion cubic metres (bcm) for the first half of the year.
Meanwhile expected shipments of LNG are also weighing on prices traders said.
The Al Khuwair tanker from Qatar docked at Britain's South Hook LNG terminal on Tuesday and three further shipments are expected to arrive in Britain in the next two weeks, according to ship-tracking data on Reuters Eikon.
Further along the curve, the March gas contract slipped 0.15 pence to 50.85 pence per therm while gas for Summer 2015 delivery was 0.15 pence lower at 46.85 pence per therm.
In the Netherlands, the day-ahead gas price at the TTF hub was 0.3 euros lower at 22.90 euros per megawatt-hour (MWh).
The benchmark European Union carbon price dipped 0.03 euro to 7.69 euros a tonne on ICE Futures Europe. (Reporting by Susanna Twidale; editing by Jason Neely)