POLL-Russian central bank seen opting for caution on Friday

* reuters://realtime/verb=Open/url=cpurl://apps.cp./Apps/cb-polls?RICRUCBIRQP

* 12 of 21 analysts expect c.bank to hold rate at 9 pct

* C.bank seen cautious given possible U.S. sanctions

* Inflation still on track to hit c.bank 4 pct target

MOSCOW, July 24 (Reuters) - Russia's central bank is expected to leave its key rate unchanged on Friday, opting for a cautious approach given the risk of new U.S. sanctions and a possible spike in food prices, a Reuters poll showed on Monday.

Twelve out of 21 polled said they expected the central bank to keep the key rate at 9 percent, holding if far above annual inflation that hovers near the central bank's target of 4 percent.

The number of those who expect the central bank to hold rates after cutting them by 25 basis points last month increased after the White House said on Sunday that U.S. President Donald Trump was open to signing legislation toughening sanctions on Russia.

"We admit that the sanction news complicated the Bank of Russia's task to ease monetary policy," analysts at Rosbank, a Russian subsidiary of Societe Generale, said in a note.

An analyst at a major Russian state bank said he would prefer to comment on the upcoming rate decision only after prospects of new sanctions against Moscow become clearer.

"We don't know yet if Trump signs the bill on tougher sanctions. If he signs it, it would be a rather serious risk for our economy and the central bank would hold over the rate cut," said Stanislav Murashov, an analyst at Raiffeisen Bank in Moscow.

The other argument for postponing a rate cut, which would deprive the rouble of some support from investors, is a recent spike in consumer prices. Inflation sped up to 4.4 percent in June from 4.1 percent in May, spurred by higher food prices amid poor harvest.

Analysts and agriculture producers warn that attempts by Russia's central bank to bring inflation to a post-Soviet low of 4 percent this year may come down to the price of vegetables.

"I think the decision is in a fine balance, although my feeling is that the CBR can't afford to ignore the June CPI print as it clearly puts the central bank in an uncomfortable position," said Ivan Tchakarov, chief economist at Citi in Moscow.

"The (bank) may not cut the key rate till September in order to become sure, that the disinflation continues," said Anton Struchenevsky, chief economist at Sberbank CIB.

But Rosbank, Raiffeisen and seven other experts among 21 polled by Reuters still expect the central bank to trim the key rate to 8.75 percent.

"We note that it will be a close call between another rate cut and a pause, but we are still going for a 25bp rate cut on Friday," said Christopher Shiells, an analyst at Informa Global Markets.

The central bank would avoid trimming the key rate this week only if there is a large-scale sell-off on the currency and debt markets, Rosbank said in a note to clients.

(Writing by Andrey Ostroukh Editing by Jeremy Gaunt.)