UK GAS-Prices decline on higher flows through Vesterled

* Higher Vesterled flows offset lower Langeled flows

* Colder weather forecast from April 22

* LNG imports from the United States to create U.S (Other OTC: UBGXF - news) .-UK price link

LONDON, April 19 (Reuters) - British prompt gas prices declined on Tuesday morning as a surge in flows through the Vesterled pipeline from Norway offset lower flows through Langeled.

The day-ahead contract was down 0.15 pence at 28.85 pence per therm at 0728 GMT, while gas for immediate delivery was also 0.15 pence lower at 29.10 pence.

UK Continental Shelf supply increased on Tuesday to 135 million cubic metres (mcm) per day, from 121 mcm/day the previous morning, because of higher flows through the Vesterled pipeline from Norway.

Stronger flows through Vesterled were offsetting lower flows through the Langeled pipeline because of an outage at Gassco's Easington terminal and gas field maintenance.

The National Grid website said the system was actually undersupplied by 7.7 mcm on Tuesday morning, with demand forecast at 245.6 mcm and flows at 237.9 mcm/day.

Looking further forward, the latest weather models show colder temperatures from April 22 for two weeks, so demand for gas for heating should rise.

"Colder forecasts for the UK and planned UK Continental Shelf maintenance events this week should help provide support for spot prices," said analysts at London-based consultancy Energy Aspects.

In the Dutch gas market, the day-ahead price at the TTF hub was down 0.20 euros at 11.57 euros per megawatt hour. In the European carbon market, front-year EU allowances edged up by 0.07 euros to 5.54 euros a tonne.

U.S. LNG

Further pressure on European gas prices is likely to come in the future as more liquefied natural gas (LNG) is imported into Europe because of limited demand in Asia, the Middle East and South America.

"Higher LNG import levels into Europe are a trend we expect to continue as LNG production levels grow in the coming years," Barclays (LSE: BARC.L - news) said in a research note.

If between 30 percent and 35 percent of 2015-2020 incremental LNG volumes are imported into Europe, that equates to between 45 billion cubic metres (bcm) and 52 bcm of additional volumes. European demand was about 475 bcm last year.

"This should be seen as a positive for industrial, commercial and residential consumers of natural gas in the region, as it would likely mean some of the lowest sustained prices in more than a decade," the note said.

In addition, the start-up of Henry Hub-linked LNG exports will create a link between U.S. and British natural gas prices.

"As U.S. LNG exports ramp up, we expect market forces increasingly to close the arbitrage window between the regions," Barclays said. (Reporting by Nina Chestney; Editing by David Goodman)