The Bank of England will flood the market with another 50 billion pounds of cash next week as Britain's economic growth outlook deteriorates and falling inflation gives the central bank room to offer further support, a Reuters poll found.

All but two of the 55 economists polled this week expected more money printing, or quantitative easing, to be announced next week. That is a sharp turnaround from just a month ago when only two of 50 expected the Bank to press the button in June.

The Monetary Policy Committee already was narrowly split on this month's decision, with Governor Mervyn King in the minority voting for more money printing, as the darkening euro zone outlook plays increasingly on policymakers' minds.

"There is a cloud of uncertainty that is weighing on the UK from the euro zone. In light of the 5-4 split, and comments from the governor, July now seems the most likely month for more QE," said Simon Wells at HSBC.

The poll gave a median 75 percent chance the MPC would restart the printing presses on July 5 and add to the 325 billion pounds it has already pumped into the money supply to stimulate growth.

That is broadly unchanged from a snap poll after the minutes of the June meeting were released last week, which gave a median 80 percent chance of more QE.

Median forecasts show the Bank will later add another 25 billion pounds, stopping at 400 billion pounds, higher than the 375 billion pounds seen in last week's poll.

Three economists are predicting a total spend of 500 billion pounds, about one-third of Britain's gross domestic product.

King said on Tuesday that the economic outlook had worsened markedly in the space of just six weeks as the euro zone crisis deepens and signs grow that a global slowdown is taking root in the United States and emerging markets.

"The euro zone crisis is potentially going to worsen over the summer. We are likely to see a protracted downside period of economic activity in the euro zone and that will have additional risks for the UK," said David Page at Lloyds Banking Group, one of the three with a 500 billion pound forecast.

The debt crisis that began in Greece over two years ago has spread across the continent, threatening the future of 17-nation euro currency. Cyprus became the fifth member of the bloc to seek assistance earlier this week.

The European Central Bank will next week cut interest rates to a new record low of 0.75 percent, and it may have to take more emergency measures to placate financial markets, a separate poll found.

A darkening outlook for the world's biggest economy pushed the U.S. Federal Reserve last week to extend its "Operation Twist" programme by $267 billion. It will sell that amount of short-term securities to invest in long-term ones, with the aim of further pressing down yields.

The British economy contracted in the first quarter of the year, slipping back into recession. Apart from a bounce as London hosts the Olympic Games this summer, the economy is not expected to rebound anytime soon.

Inflation has been steadily declining in recent months. While still above the Bank's 2 percent target at a two-year low of 2.8 percent in May, it may give it a little more room to manoeuvre. It is seen averaging 2 percent next year.

MP SEE

The central bank chief's gloomy comments to MPs on Tuesday will have bolstered expectations the Bank will launch a new round of asset purchases.

King, entering his final year as Bank Governor, told parliament's Treasury Committee he had been very keen to engage in asset purchases and that there was nothing in principle against cutting Bank Rate further.

The Bank slashed interest rates to a record low of 0.5 percent more than three years ago and none of the 55 poll respondents saw a change until April at the earliest. Medians suggested it will be at least 2014 before there is any movement.

The nine-person Monetary Policy Committee was split 5-4 in favour of holding tight at this month's meeting, with Governor Mervyn King outvoted for the first time in five years on his call for more stimulus.

Most members judged that some further economic stimulus was either warranted immediately or later, the minutes said.

"It seems that those who remained on the sidelines did so out of a desire to wait for the outcome of political events in Europe, and for more detail on the collaborative efforts planned between the Bank-Treasury to help ease banks' funding costs," said Danielle Haralambous at 4CAST.

"Now that such events have passed and the uncertainty associated with them has dissipated, there are fewer barriers to the QE vote, and we can assign a much higher likelihood to the possibility that a QE extension becomes policy in July."

(Polling by Aakanksha Bhat and Namrata Anchan; Editing by Catherine Evans)