* STOXX 600 flat, blue chips negative
* Weir surges after upping 2017 forecasts
* Telenor also jumps after Q2 beat
* Miners rally as China GDP strong (ADVISORY- Follow European and UK stock markets in real time on the Reuters Live Markets blog on Eikon, see cpurl://apps.cp./cms/?pageId=livemarkets)
By Kit Rees and Helen Reid
LONDON, July 17 (Reuters) - European shares gave back early gains in thin volumes on Monday, as a busy few weeks of earnings reports from top regional and U.S. firms got underway.
The pan-European STOXX 600 index steadied at the close after touching a three-week high, while blue chips turned negative to trade 0.3 percent lower.
Last week, European indexes enjoyed their strongest week in more than two months as investors quickly bought the dip spurred by central banks turning slightly hawkish.
Second-quarter results season kicked off in the United States last Friday with numbers from Citigroup and JPMorgan.
Analysts are expecting earnings to grow 9 percent year-on-year for European firms, compared with 8 percent for U.S. ones, according to Thomson Reuters I/B/E/S.
British engineer Weir Group was the biggest STOXX riser, jumping more than 8 percent after increasing its forecasts for its oil and gas units, thanks to strong North American drilling activity.
"The extent of the Oil & Gas upgrades are significant, obviously, and shows how volatile this end market can be. This time, it's going in the group's favour, and they are very much benefiting from it," analysts at Jefferies said in a note.
Updates from some Nordic firms spurred sizeable moves too, with shares in Norway's Telenor jumping more than 8 percent. The telecoms firm raised its outlook for 2017 earnings margins after its operating results beat expectations.
On the downside, shares in Swedish medical technology firm Getinge dropped 9 percent after its second quarter core profits lagged forecasts and it booked a remediation provision for a facility in Hechingen.
"While there are some encouraging signs of margin improvement supported by gross margin and its cost saving measures, the top line and order dynamic for the company is still weak," said Berenberg analysts.
Swedish engineers Atlas Copco and Sandvik also fell 4.6 to 7.5 percent after their results, which slightly underperformed high expectations.
Peer Alfa Laval, on the other hand, surged to a record high after its earnings beat forecasts after the firm said it had seen a surprisingly strong order intake.
Industrial machinery firm GEA Group fell 5.6 percent after the company cut its profit guidance.
"It remains difficult to separate weakness in some end markets from internally generated problems, but our take is that most of the issues are self-inflicted," said Jefferies analysts.
While the majority of sectors were in positive territory, basic resources stocks were the biggest gainers, up 1.3 percent, with miners Anglo American, Glencore and Antofagasta leading the charge higher after the price of copper hit a 4-1/2 month high following strong GDP figures from China, the world's biggest metals consumer.
And British online grocer Ocado crept up the STOXX 600 to finish among top gainers, with its best day since June 19 when speculation was swirling over its potential to be a takeover target after the Amazon-Whole Foods deal was announced.
Ocado boosted European retailers, which led sector gains. (Reporting by Kit Rees; Editing by Raissa Kasolowsky and Mark Potter)