The FTSE ploughed down through support levels on Tuesday as slowing global growth and Greece's dithering over its debt swap plan intensified pressure on riskier assets, prompting a flight to safety and sparking fears of a deeper sell-off.

London's blue chip index <.FTSE>, which is heavily weighted towards riskier banking and commodity stocks, posted its biggest one-day fall since December 14, shedding 109.02 points or 1.9 percent to 5,765.80.

The UK's benchmark index fell through various technical levels including its 50-day moving average and more importantly the uptrend support that had been in place since late November.

The FTSE 100 move lower today has taken us through uptrend support ... 5,700 would beckon near term on a break here (5,870 level), a London-based trader said.

Commodity stocks led the fallers as investors fled to safer havens such as the dollar <.DXY>, sparking a fall in the price of crude oil, off recent highs, and a retreat in base metal prices, which crimp earnings capabilities of integrated oils <.FTNMX0530> and miners <.FTNMX1770>.

Russian gold mining group Polymetal International
dropped 6.3 percent as UBS downgraded its rating to neutral from buy and cut its target price and earnings estimates.

UBS said without catalysts such as a strong gold/silver price or expansion in reserves base, the stock is unlikely to outperform the sector in the short term.

The fall in commodity stocks coincided with renewed fears of recession in the euro zone as a collapse in household spending, exports and manufacturing sucked the life out of the region's economy in the final months of 2011.

Accentuating the decline, 2011 GDP growth in emerging economy Brazil slipped to 2.7 percent from a 2010 figure of 7.5 percent. That followed China cutting growth forecasts on Tuesday.

Worries over a European recession, emerging market economies -- the last bastion of real growth -- and the Greek debt swap conundrum have done nothing to help fragile sentiment, which has been compounded by the recent low volume rally, Jimmy Yates, head of equities at CMC Market, said.

FINANCIALS FLAIL

Traders said the FTSE 100 index extended losses on rumours, later denied by Athens, that Greece would have to push back Thursday's deadline for agreeing a debt swap with private creditors and avert a default that would endanger debt-laden Italy and Spain.

A disorderly Greek default would cause more than 1 trillion euros of damage to the euro zone and could leave Italy and Spain dependent on outside help to stop contagion spreading, the main bondholders group has said.

Banks <.FTNMX8350> and insurers <.SXIP>, both of which helped the FTSE 100 to strong gains early in 2012, fell as financials with heavy exposure to Europe's debt crisis were among the stocks worst hit.

Volatility <.VFTSE> -- a crude gauge of investor pessimism -- spiked 19 percent.

Aviva shed 4.7 percent as Exane BNP Paribas downgraded its rating for the British insurer to underperform from neutral and reduced its target price and earnings estimates.

Declining earnings will increase pressure for a further reduction in debt leverage. In the meantime, Aviva's share price has re-rated based on the recovery in Italian government bonds over the last three months, Exane BNP Paribas said.

British aircraft parts supplier Meggitt , which had gained 10 percent in the past month. fell 4.9 percent after it delivered strong growth in 2011 profit.

Essar Energy and Cain Energy - both seen as likely candidates to leave the FTSE 100 in this week's reshuffle - shed 5.1 and 3.3 percent respectively, while Hargreaves Lansdown was the main FTSE riser, up 3.1 percent, as tracker funds jostled postions ahead of the announcement.

(Editing by David Cowell)