By Andy Bruce

LONDON (Reuters) - Hailed by investors as a weapon to fight off recession but slammed by critics for fuelling inequality, quantitative easing looks set for a comeback in Britain as the Bank of England tries to shield the economy from the fallout of Brexit.

The central bank is poised to cut interest rates as soon as Thursday and will probably follow up soon afterwards by reviving the massive bond-buying program that it credits with helping to shore up the economy after the global financial crisis.

Economists are now asking how the BoE might tailor QE to meet the problems Britain faces in the aftermath of last month's vote to leave the European Union - a result that threw the country into political chaos and has sparked fears of recession.

Most economists polled by Reuters expect the BoE will cut rates to a new record low of 0.25 percent on Thursday, followed by an extension of the QE program which it adopted as the financial crisis raged in early 2009, probably in August.

Following the lead of the central banks in Japan and the United States, the BoE created 375 billion pounds ($496 billion) between 2009 and 2012 to buy government bonds to get money flowing through the economy.

The plan boosted asset prices but led to criticism that the BoE had provided most help to wealthy owners of shares and property. Supporters of QE say it has helped all households by boosting employment and reducing borrowing costs broadly.

The Reuters poll showed the BoE is expected to announce 50 billion pounds of extra asset purchases next month when it will factor the Brexit hit into its economic forecasts.

"Given how little room the BoE has to cut rates ... if they want to ease policy much more, they'll have to go for more QE," said Martin Beck, an economist with Oxford Economics.

Bank of England Governor Mark Carney has said he does not favor cutting interest rates into negative territory.

How effective more QE will prove to be, and whether the BoE will stick to buying only government bonds, is less clear.

Former BoE policymaker David Miles has argued that bond purchases work best when financial markets are dysfunctional. After the initial shock of the June 23 Brexit vote, markets have functioned well, Carney has said.

On the other hand, one of the BoE's current rate-setters Martin Weale has said QE remained effective after the worst of the financial crisis, citing evidence that it continued to work from 2010 to 2014.

His faith in QE was one reason why he was willing to vote for higher interest rates in recent years.

"The question is how they do it - will they do it through the conventional gilt approach, or would they take a more particular approach toward different asset classes?" asked Beck

LET'S TWIST AGAIN?

QE has been adopted by the developed world's four big central banks, swelling their balance sheets with trillions of dollars worth of assets. (For a graphic, click on http://tmsnrt.rs/29Jg8Td)

The BoJ pioneered the purchase of government bonds with new money in 2001 to fight deflation. More recently, the ECB has tweaked QE to purchase corporate bonds on a large scale.

The BoE might do likewise if signs emerge that British business investment is falling fast and corporate funding costs start rising. It purchased a small amount of corporate bonds when it first started QE.

For now though, gilts will again probably be the primary target for more asset purchases, said Peter Dixon, an economist with Commerzbank.

"Because interest rates in the UK are higher than they are in the euro zone, they have a lot more headroom to buy gilts rather than move into other areas of the market," he said.

Another option is a reversal of the U.S. Fed's "Operation Twist" under which the BoE would sell long-dated stock of gilts and replace them with short-dated bonds, which could help homeowners.

"This would put downward pressure on fixed-term mortgage rates through lowering short-dated gilt yields and swap rates," Investec economist Philip Shaw said. More than 80 percent of new mortgages are based on fixed rates and short maturities, he said.

Tim Davis, an economist at Fathom Consulting, also advocated this tactic. "An 'Operation Anti-Twist' would be more of a shock to the market in our view," he said.

(Editing by Willliam Schomberg and Gareth Jones)