* reuters://realtime/verb=Open/url=cpurl://apps.cp./Apps/econ-polls?RIC=CNGDP%3DEC I poll data
* China economy seen growing 6.7 pct y/y in Q4, vs Q3's 6.8 pct
* Battle on debt risks, pollution may weigh on growth
* Dec factory, retail sales and investment seen slightly weaker
* Q4 GDP data, Dec activity data due Jan 18 at 0200 GMT
BEIJING, Jan 15 (Reuters) - China's economic growth is expected to have slowed slightly in the fourth quarter from the previous quarter, a Reuters poll showed, as the government extended a crackdown on debt risks and factory pollution.
Policymakers in the world's second largest economy have been trying to contain financial risks and slow an explosive build-up in debt without stunting economic growth.
The poll of 61 analysts showed growth in gross domestic product likely slowed to 6.7 percent on a year-on-year basis, down from 6.8 percent in the third quarter.
The expected moderation comes on the back of a cooling property sector, pollution curbs that have hit factory activity and a rise in corporate borrowing costs.
"We see Q4 GDP (growth) moderating slightly to 6.7 percent year-on-year, with softer quarter-on-quarter momentum," analysts at UBS said in a note.
GDP growth for the full-year of 2018 could slow to 6.4 percent from an expected 6.8 percent in 2017, as "property sales and construction slow on sustained tight policies and fading market momentum" and infrastructure investment decelerates on tighter local government financing, the UBS analysts said.
A better-than-expected gross domestic product reading could lift stocks and global commodity prices, and boost bullish sentiment on the yuan, which has gained about 1 percent against the dollar so far this year, following a 6.8 percent rise last year.
Analysts' forecasts for December quarter growth ranged from 6.5 percent to 7 percent, with modest upside surprises tipped after Premier Li Keqiang said last week that the economy is expected to have grown 6.9 percent last year.
China will release fourth-quarter and 2017 GDP on Thursday, along with December industrial output, retail sales and fixed asset investment data.
Economists in the poll estimated GDP grew 1.6 percent quarter-on-quarter, easing from 1.7 percent in the third quarter, though only 16 analysts gave sequential forecasts.
China's exports and imports growth slowed in December after surging in the previous month, adding to signs of ebbing economic momentum. Solid exports have been a boon for Chinese policymakers.
Meanwhile, China's bank lending halved in December as the government kept up its campaign to curb financial system risks, but banks still managed to dole out a record amount for the year amid the tighter scrutiny.
Policy sources told Reuters previously that China will still keep its GDP growth target at around 6.5 percent in 2018 as Beijing seeks to balance efforts to reduce debt risks while keeping the economy on a steady footing.
The central bank is likely to keep its grip on money supply this year to help contain risks, but no increases in benchmark interest rates are expected any time soon following a recent rise in corporate funding costs, according to the sources.
SLIGHTLY WEAKER DECEMBER DATA EXPECTED
Additionally, analysts will be looking at December data on factory output, investment and retail sales, also released on Thursday, for clues on economic momentum heading into early 2018.
Economists expected December factory output to have grown 6 percent from a year earlier, slowing from November's 6.1 percent.
China's commodities buying spree eased slightly in December, with copper, iron ore and crude oil imports all falling from bumper levels a month earlier, the latest sign that Beijing's anti-smog crackdown is slowing industrial activity.
Retail sales are seen growing 10.1 percent in December from a year earlier, easing slightly from 10.2 percent in November.
Fixed-asset investment is predicted to have increased 7.1 percent in 2017, easing from 7.2 percent in January-November. (Reporting by Kevin Yao in BEIJING and Shaloo Shrivastava in BENGALURU; Editing by Sam Holmes)