* FTSE 100 flat, trading volumes light
* Johnson Matthey up after results
* Miners hit by weak Chinese data
By Tricia Wright
LONDON, Nov 21 (Reuters) - Britain's top shares steadied on Thursday as solid earnings from the likes of Johnson Matthey alongside robust U.S. economic data offset concerns over the outlook for U.S. monetary policy.
However, some traders felt there was scope for further falls in the market which, has been trending lower since late October.
The FTSE 100 was up 2.98 points at 6,684.06 points by 1536 GMT, having recovered from a session low of 6,643.47 and after losing ground in the previous two days. Volumes were light, at about half of the 90-day daily average.
The index is trading around 2 percent below a five-month high of 6,819 hit on Oct. 30, shaving its advance in 2013 to around 13 percent.
"I think we are still in a sell-off," Mike van Dulken, head of research at Accendo Markets, said.
"The tick back up ... from the lows is nice to see but you've still got big resistance at 6,710."
He said that, should support at 6,640 give way, the index could fall as far as mid-November lows of around 6,610.
Johnson Matthey, the world's largest maker of catalysts to control car emissions, topped the FTSE 100 leader board, up 3.6 percent, after unveiling a 13 percent rise in first-half profit, helped by increased global production of cars and trucks.
"A strong set of numbers ... The outlook remains slightly cautious but notwithstanding any more negative news in this space we expect to see some more earnings upgrades through the next couple of years," said Atif Latif, director at Guardian Stockbrokers.
Sentiment on Thursday was helped by data releases from the United States indicating stronger labour market conditions and subdued inflation pressures.
But the market's progress was limited by minutes of the Fed's Oct. 29-30 meeting showing bank officials felt they could start scaling back the asset purchase programme at one of its next few meetings if economic conditions warranted it.
The stimulus has proved a major driver for the UK benchmark index, which has risen around 20 percent in the past year as investors have moved out of safe bonds and into higher-yielding assets, such as stocks.
Some traders reckon this has left valuations looking stretched, with the FTSE 100 trading on a 12-month forward price/earnings ratio of 12.7 times, above its 10-year average of 12 times, according to Thomson Reuters Datastream.
"Although the markets knew (stimulus withdrawal) was coming, and to an extent has been priced in for a while now, I believe there is scope for a sell-off as some traders look to close positions and lock in profits," Sanlam Securities' head of trading Mark Ward said.
News of slowing factory growth in top metals consumer China also capped Britain's miners-heavy exchange.
Antofagasta, off 1.4 percent, was downgraded by UBS on Thursday, to "neutral" from "buy", with the investment bank citing concern over the outlook for copper.