* Liffe certified stocks fall to 31,420 tonnes as of Nov.25
* Rabobank forecasts robusta at $1,550/tonne Q1 2014
LONDON, Dec 19 (Reuters) - Robusta coffee prices are expected to slide after being one of the best performing commodities in recent weeks, as a record crop in top grower Vietnam will ensure a sell off in the new year, analysts said.
Coffee roasters have run down their inventory of the caffeine rich variety of beans, heavily used in their instant coffee blends, anticipating prices will come off as farmers cash-in their crop.
Robusta coffee futures rose more than 20 percent from the start of November to hit a near four-month high of $1,813 per tonne last week, aided by farmers withholding sales and exchange stocks being drawn down, but analysts say this is a short term phenomenon and the gains were not sustainable.
"Literally it's a question of who is going to blink first," Kona Haque, analyst at Macquarie Bank said.
"This really is a short term supply squeeze and if the roasters can ride it out until such time that the Vietnamese growers think they need to start selling then that will work out in their favour."
Haque said any signs of significant volumes of sales on the physical market would trigger a sharp sell off in robusta futures.
Traders estimate farmers' carryover stocks from the previous season were at a record high and given Vietnam is expected to have only sold up to 20 percent of its current crop thus far, there was potential for massive selling pressure from January onwards.
"Farmers are starting to sell around these levels," a European analyst said.
"Roasters are reasonably well covered, not a hugely long cover, but they're not in a panic."
Vietnamese farmers typically sell at least half of their crop ahead of the Tet holiday which is less than six weeks away.
This has fallen to around a third in recent years, however, as they have become better financed, traders said.
EXCHANGE STOCKS DWINDLE
Firm prices on the physical market in Vietnam have led roasters to use the cheapest beans available in warehouses in Europe.
Vietnamese farmers are benefiting from falling exchange-certified stocks which back the Liffe futures contract, which fell to 31,420 tonnes as of Nov.25, according exchange data which is updated fortnightly.
Dealers said it was just a matter of time before there was convergence between the futures and physical markets to ensure exchange coffee stocks were rebuilt.
"Certifieds are drawing sure, but we do have replenishment just around the corner, it's just a matter of how low the certs go," a London-based broker said.
"We've probably got another couple of reasonable size draws and then we should see that ease off."
Liffe March robusta coffee was down $17 or 1 percent at $1,682 as at 1144 GMT on Thursday.
Rabobank forecast that robusta coffee prices would fall around 8 percent to trade at $1,550 per tonne in the first quarter of 2014.
(Editing by William Hardy)