Sterling has fallen to a two-and-a-half-year low against the dollar after manufacturing figures for February revealed a fall in output.
The closely watched Markit/CIPS purchasing managers' index showed a slump in activity to 47.9 - well below the 50 level which separates growth from contraction.
It was the first time since last November the sector's activity shrunk, and followed 50.2 in January.
The value of the pound slipped following the data, and fell below $1.50 on Friday afternoon - its lowest since the middle of 2010.
Sterling has only been beneath the $1.50 mark for four of the 200 years since the US Declaration of Independence.
The last time it was at this level was briefly during the 2010 election and coalition-building process, and before that the 2008/09 recession.
Chris Williamson, chief economist at Markit, said the manufacturing data increased the chance that Britain will slip back into recession.
"The return to contraction of the manufacturing sector is a big surprise and represents a major set-back to hopes that the UK economy can return to growth in the first quarter and may avoid a triple-dip recession," he said.
"The data so far this year point to manufacturing output falling by as much as 0.5%, meaning a strong rebound is needed in March to prevent the sector from acting as a drag on the economy as a whole in the first quarter."
The struggling sector contributed to the UK's worse-than-expected 0.3% decline in output in the fourth quarter of last year, and a negative reading for the first quarter of 2013 would see the UK enter a triple-dip recession.
Nawaz Ali, a market analyst with Western Union, said the manufacturing data could increase pressure on the Bank of England (BoE) to launch a new round of asset purchasing - or quantitative easing - as early as next week.
"The data is a major setback for sterling and the size of the manufacturing decline indicates that there is still a chance the British economy may suffer an unprecedented triple-dip recession," he said.
"The data also adds to growing concerns that not only could the BoE re-start monetary printing in March, the central bank's new flexible inflation strategy puts it in a position to launch a prolonged period of asset purchases, similar to what the US have done and what the Bank of Japan is planning to do."
More quantitative easing is likely to hit sterling further because it increases its supply and drives the currency's exchange value lower.
So far this year, sterling - which was also hit by Moody's downgrade of the UK's credit rating - has lost 7.5% against the dollar.
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