* System oversupplied by around 8 mcm/day
* Within-day gas down 0.50 p at 28.10 p/therm
LONDON, April 4 (Reuters) - British wholesale gas prices declined on Monday morning because of an oversupplied system.
Gas for day-ahead delivery was down 0.17 pence at 28.25 pence per therm at 0735 GMT from the previous settlement, while gas for immediate delivery dipped by 0.50 pence to 28.10 pence per therm.
"The market is long this morning, which is putting pressure on prices," a gas trader said.
Supply from the UK Continental Shelf was relatively strong at 150 mcm, while Norwegian flows through the Langeled pipeline were at 57 mcm/day.
The weather is forecast to be colder by the end of this week, the UK's Met Office said, before turning milder next week.
Further along the curve, gas for May delivery was down 0.48 pence at 27.00 pence per therm.
In the Dutch market, day-ahead gas prices at the TTF hub inched down by 0.13 pence to 11.40 p/therm.
In the European carbon market, benchmark EU allowances declined by 0.09 euro to 5.09 euros a tonne.
(Reporting by Nina Chestney; Editing by Dale Hudson)