Oil production fell to below an average of 1.4 million barrels per day (bpd), over 12 per cent less than in April last year. Gas was also down 3.2 per cent on the year to 8,170 million standard cubic feet per day (mmcfd).
The UK's continental shelf "is maturing rapidly and an increasing share of investment spending is needed just to maintain current production levels," the bank said.
"Recent production data provide mounting evidence that the long- term decline of the North Sea will not come to a halt," it said about the production, which has been falling since 2000.
Despite the fall, the average daily value of oil rose due to rising prices to Pnds 81.76 m, its highest level in year, when production was nearly 200,000 bpd more.
In January, the Royal Bank of Scotland dismissed a mini re-surge in oil prices at the time as being short-lived, incorrectly predicting that rates would instead slowly decrease to around only 45 dollars per barrel.
