FTSE has biggest one-day gain in a week, buoyed by ECB policy stance

* FTSE 100 up 1.8 pct at close following Draghi's comments

* EasyJet (Other OTC: EJTTF - news) up 5.4 pct to highest in over three months

* Morrisons up 4.7 pct on report of sector merger interest

* Battered miners Anglo American (LSE: AAL.L - news) , Glencore (Xetra: A1JAGV - news) stage rebound (Updates closing prices)

By Kit Rees and Lionel Laurent

LONDON, Sept 3 (Reuters) - UK shares had their biggest one-day gain in a week on Thursday, boosted by a commitment from ECB chief Mario Draghi to boost the central bank's asset-purchase programme if needed to offset the effects of a riskier economic backdrop.

The FTSE 100 blue-chip index was up 1.8 percent at 6,183.09 points at its close.

"It (Other OTC: ITGL - news) looked to me as if (Draghi) was extremely dovish in his perception of the economic environment," said Jeremy Batstone-Carr, analyst at Charles Stanley (LSE: CAY.L - news) .

"The market is also of the opinion that the ECB, without wishing to be bounced into a knee-jerk policy response to what's happened ... is expressing some disquiet about the continued weakness in the oil price, and of course obvious weakness across emerging markets and in particular China."

Data showing Britain's services sector recorded its weakest growth in more than two years last month also supported stocks, with investors seeing the benign outlook for inflation as a sign that domestic monetary policy will also stay loose.

EasyJet was up 5.4 percent, having hit its highest level since May, after the airline raised its full-year profit outlook to forecast growth of up to 21 percent.

"EasyJet's numbers were good, this is a good market rebound," said Mark Ward, head of execution trading at Sanlam Securities in London. "Overall sentiment is a bit better today."

Morrison Supermarkets was up 4.7 percent after a report in the Daily Telegraph newspaper signalled South African billionaire Christo Wiese, who recently bought Virgin Active and New Look, is training his sights on Britain's struggling supermarket industry.

Miners Anglo American and Glencore staged a rebound, rising around 6 percent, even after Standard & Poor's cut its outlook for Glencore to 'negative' from 'stable'.

The FTSE 100 is due to be reshuffled on Sept. 21 to include housebuilder Berkeley Group and drop Weir Group . (Editing by John Stonestreet/Ruth Pitchford)