(Recasts to show copper up, updates prices)
SYDNEY, July 11 (Reuters) - Copper turned positive in late Asia trading on Tuesday, boosted by stronger steel prices in China.
"Copper got a plug from a big jump in steel prices and also stronger regional shares," a commodities trader in Perth said.
On the Shanghai Futures Exchange, the most-active steel rebar contract galloped more than 3 percent higher.
But the trader warned that as investors awaited testimony from Federal Reserve Chair Janet Yellen for clues on when the central bank would tighten U.S. monetary policy, copper could come under pressure.
Higher rates mean higher borrowing costs, which normally translate into a stronger U.S. dollar which leads to lower metal prices.
Yellen's semi-annual monetary policy testimony is scheduled before Congress on Wednesday and Thursday.
* Three-month copper on the London Metal Exchange rose 0.4 percent to $5,845 a tonne by 0730 GMT, reversing losses from the previous session.
* The most-traded copper contract on the Shanghai Futures Exchange ended 0.41 percent higher at 47,050 yuan ($6,912.92) a tonne.
* COPPER STRIKE: Workers at the Zaldivar copper mine in Chile, owned by Antofagasta and Barrick Gold Corp , voted to approve a strike on Monday after talks with the company failed.
* NORSK HYDRO: Norwegian metals firm Norsk Hydro will take full ownership of aluminium products maker Sapa by buying a 50 percent stake from conglomerate Orkla
* Steel related LME base metals nickel and zinc showed modest gains in step with firmer China steel futures. The most-traded ShFE nickel and zinc contracts were also up on the day.
Three month LME copper
Most active ShFE copper
Three month LME aluminium
Most active ShFE aluminium
Three month LME zinc
Most active ShFE zinc
Three month LME lead
Most active ShFE lead
Three month LME nickel
Most active ShFE nickel
Three month LME tin
Most active ShFE tin
ARBS ($1 = 6.8026 Chinese yuan)
(Reporting by James Regan; Editing by Amrutha Gayathri and Biju Dwarakanath)