An unexpected split on the Bank of England's rate-setting Monetary Policy Committee in February has revived expectations that the central bank will engage in further stimulus to shore up the U.K. economy later this year.

Minutes of the MPC's February policy meeting showed that policy makers Adam Posen and David Miles voted for a larger expansion of the BOE's bond buying program than the GBP50 billion the committee ultimately sanctioned. They pushed for GBP75 billion of additional stimulus, saying there's a risk that a prolonged period of depressed demand could pull the inflation rate much lower than the BOE's 2% target and cause permanent damage to the U.K. economy.

Investors thought the February vote might well have been split, but figured that dissent would more likely have come from among inflation hawks on the committee like Spencer Dale, Martin Weale or Paul Tucker, who have occasionally appeared less than comfortable with endorsing stimulus while inflation remains above target.

Indeed, the minutes record that some rate-setters thought there could be a case for leaving policy unchanged in February.

"For some members, the probability of inflation exceeding the target was slightly higher than shown" in the BOE's February forecasts, the minutes record.

In the end, however, those members voted with the majority for a GBP50 billion increase in bond buying, or quantitative easing, to take the total size of the BOE's stimulus program to GBP325 billion when the new purchases are completed in April.

Rate-setters were unanimous in leaving the BOE's key interest rate at 0.5%, a record low.

In recent months, MPC members have had to strike a difficult balance between supporting a flagging economy, and retaining their credibility as inflation foes. The U.K. economy contracted by 0.2% in the final three months of last year, and few economists expect a strong recovery soon.

But the annual rate of inflation has remained stubbornly high, although it eased to 3.6% in January from 4.2% in December. The BOE sees inflation slowing to 1.87% by the final quarter of 2012, according to figures published Wednesday that supplement its February forecasts.

Its quarterly inflation report, published Feb. 15, damped but did not extinguish expectations of further QE, as it suggested the central bank could just about hit its 2% inflation target in two years without needing to buy more bonds, barring any unexpected weakness in growth.

The news that Posen and Miles felt GBP50 billion might not be enough to hit the target caused investors to reconsider that assessment. U.K. government bonds rallied after the minutes' publication, which suggests market participants expect further purchases to be made.

Economists were divided. Philip Rush, an economist at Nomura, said "the dovish activism" of Posen and Miles suggests there is already some support for such an increase in the stock of asset purchases. He expects another GBP25 billion of stimulus in May.

Economist Simon Hayes at Barclays Capital, however, said the mixed signals from the minutes haven't changed his view that February's asset purchases were likely to be the MPC's last.

"It seems clear now that it is the data that will determine whether QE has further to run, and that most MPC members view the current policy stance as appropriate," Hayes said.

Others simply thought the clearest message from the minutes was that the emerging three-way split on the committee means judging the future direction of MPC policy just got more difficult.

"Today's minutes make the U.K. policy outlook more, not less, uncertain," said Simon Wells, an economist at HSBC, who thinks a further extension of QE is likely, but not until August.