(Close): UK shares turned south in the afternoon to end with a hefty loss leaving the FTSE 100 index down 111 - or 1.7% - at 6,446.

ECB president Mario Draghi set out the details of its asset buying plan around lunchtime without giving guidance as to its size - and the markets were not happy with it.

Sainsbury's began higher, bouncing back from its downbeat trading statement on Wednesday, but ended down 4%.

Its rival shares followed suit.

Morrisons ended down 0.6% after rising 1.6%, while Tesco 1.5% to end down 1.1%.

The oil price went to a two-year low, following news that Saudi Arabia state producer Saudi Aramco had cut prices.

Brent crude for November delivery fell 1.3% to $92.91 a barrel, while US crude ended London trading flat at $90.63 a barrel.

Ted Baker shares were up 0.6% after the clothing brand reported a strong rise in first-half profits.

Pre-tax profits for the half year to 28 August rose by a third to £15.6m, with revenues up 17% to £182.2m.

Domino's Pizza rose 1% after it delivered another strong set of trading figures. UK underlying sales rose 12.9% for the 13 weeks to 28 September, although Domino's noted that its progress in turning round its German business was "slower than we would have liked".

On the currency markets, the pound fell 0.22% against the dollar to $1.6148 and dropped 0.66% against the euro to 1.2737 euros.