* ASX trades higher, March quarter GDP trumps expectations
* Banks cap gains after cartel charges against ANZ
* Healthcare stocks touch record
By Devika Syamnath
June 6 (Reuters) - Australian shares enjoyed mostly broad-based gains on Wednesday though banks weakened after top lender Australia and New Zealand Banking ANZ.AX was booked by the country's competition watchdog for alleged cartel behaviour.
The S&P/ASX 200 index .AXJO advanced 0.4 percent or 25.1 points to 6020 points by 0219 GMT. The benchmark closed 0.5 percent lower on Tuesday.
Sentiment was helped by Australia's economy expanding at its fastest annual pace in almost two years, with 3.1 percent growth in the March quarter, up from 2.4 percent in the December quarter, and beating expectations from a Reuters poll for 2.8 percent growth. were the best performing sector with mining stocks .AXMM rising about 1.8 percent to touch their highest since May 23, supported by strength in iron ore and metal prices. MET/L IRONORE/
Bloomberg cited sources saying bids from a consortia of bidders valued BHP's BHP.AX shale unit at up to $9 billion. was concerned about what price they would get, but $7 billion to $9 billion is at the upper end of what people were hoping for," said Christopher Conway, Head of research and trading at Australian Stock Report.
Mining giants BHP Billiton (LON:BLT) Ltd BHP.AX and Rio Tinto (LON:RIO) Ltd RIO.AX were both trading more than 2 percent firmer.
Elsewhere, biotherapeutics company CSL Ltd CSL.AX surged to a record after gaining more than 2 percent and was among the top boosts to the main board. The index of healthcare stocks .AXHJ also achieved a record.
Energy stocks like Woodside Petroleum WPL.AX and Origin Energy ORG.AX benefitted from oil prices that recovered on data showing a decline in U.S. crude inventories. The gas suppliers traded 2.5 percent and 1.9 percent higher, respectively. O/R
Bucking the trend, bank stocks .AXFJ charted a 0.6 percent decline as charges of cartel behaviour against ANZ added on to the almost daily reports of misdemeanor in the financial sector emerging from an Royal Commission inquiry. country's "Big Four" banks lost between 0.5 percent and 1.6 percent.
The charges against ANZ, Deutsche Bank AG DBKGn.DE and Citigroup Inc (NYSE:C) C.N , which were announced after markets closed on Tuesday, can carry hefty fines and 10-year prison terms.
Across the Tasman Sea, New Zealand's benchmark S&P/NZX 50 index .NZ50 was up 0.1 or 11.35 points to 8768.39 at 0213 GMT. The index closed at a record in the previous session, up 1.4 percent.
Healthcare stocks contributed most of the gains on the index.
Fisher & Paykel Healthcare FPH.NZ added as much as 3.8 percent to its best level since December 2017 while Ryman Healthcare RYM.NZ touched a record, up 1.7 percent.