A man works on the production line at the Toyota factory in Derby, central England, March 7, 2011.

Dec 7 British industrial output suffered its biggest monthly drop in more than four years in October after the temporary shutdown of a major oilfield, while factory output also sagged, official figures showed on Wednesday.

While oil production is likely to bounce back once the North Sea field completes routine maintenance, the weak performance from manufacturers may raise doubts about how much of a boost they are getting from the big fall in sterling since Britain voted to leave the European Union in June.

Figures for October showed industrial output fell 1.3 percent month-on-month after a 0.4 percent decline in September, the ONS said on Wednesday, bucking economists’ predictions in a Reuters poll for it to rise by 0.2 percent.

The monthly decline was the sharpest since September 2012, and contributed to a 1.1 percent fall on the year, the steepest since August 2013.

"October saw a sharp fall in UK oil output, largely down to the total shutdown of the major Buzzard oil field," ONS statistician Kate Davies said.

Oil production was 10.8 percent down on the month, the biggest fall since September 2012, when the Buzzard oilfield also suffered production difficulties.

Output in manufacturing sagged by 0.9 percent – the biggest fall since February – after a 0.6 percent monthly rise in September. Economists polled by Reuters had expected manufacturing output to increase 0.2 percent.

Looking at the three months to October as a whole, industrial output was 0.9 percent lower than the previous three month period, compared with a 0.4 percent contraction in the three months after the Brexit vote.

The ONS said October saw falls in factory output across a range of sectors, contrasting as before with a generally more upbeat picture from earlier private-sector surveys.

Sterling fell to a 31-year low against the dollar in October on concern that Prime Minister Theresa May would favour curbing migration from the EU over retaining British firms’ export opportunities.

Since then sterling has strengthened, though Britain’s government has given little detail on what trade-offs it might make when it starts formal Brexit talks early next year.

A survey of factory purchasing managers last week showed that activity slowed in November as manufacturers grappled with costlier raw materials after the fall in sterling.

The Confederation of British Industry also reported inflation pressures, but said output was expected to pick up at the fastest rate in nearly two years on the back of stronger orders.

(Reporting by David Milliken and Paul Sandle)