LONDON — Opec has agreed informally that it needs to cut production by at least 1m barrels a day – at least 4 per cent – in order to boost the falling price of oil. The majority of the cartel’s members back a voluntary reduction over the coming weeks and the deal could be ratified as early as the group’s mid-December meeting in the Nigerian capital of Abuja. ‘Opec is going to defend a price floor for its oil of $50-$55 a barrel,’ said one Opec official. The price of Opec’s crude oil on Wednesday fell to $55.27 while Brent oil futures traded in London slipped 33 cents to $58 a barrel, 26 per cent below their July peak. Prices have fallen as demand in the US has waned and the likelihood of a supply shortage caused by Iran’s stand-off with the west has diminished. Saudi Arabia, Opec’s most important member, is unhappy with the move towards voluntary cuts, but at the same time the kingdom has already quietly cut its production by 200,000 barrels a day over the past two months. It would rather reach a clear public position at the cartel’s meeting in Abuja. […]