* Q1 GDP down 3.2% on quarterly basis
* Central bank mandate news also weigh
* Stocks lifted by heavyweights (Updates prices, adds stocks)JOHANNESBURG, June 4 (Reuters) - South Africa's rand slumpedon Tuesday after data showed the worst quarterly economiccontraction in a decade at the start of 2019, while stocksgained.The rand was also hammered by news that South Africa'sgoverning party has agreed to expand the central bank's mandateto include employment and growth as well asinflation. Investors are nervous about any changes that could curb theindependence of the South African Reserve Bank (SARB).At 1530 GMT, the rand was 1.8% weaker at 14.7000per dollar."The problem is that the economic data release hasaccelerated even the most pessimistic concerns regarding thehealth of the South African economy," said Jameel Ahmad, globalhead of currency strategy and market research at online tradingplatform FXTM.The statistics office said gross domestic product contracteda quarterly 3.2% in the first three months of 2019, lagging the1.7% decline economists had expected and showing President CyrilRamaphosa's growth drive is struggling to gain traction.Bonds also weakened, with the yield on the benchmark 10-yearissue up 3 basis points to 8.45%.In equities, stocks strengthened as the rand weakened on thepoor GDP numbers.
The broader All-Share index closed stronger 0.38%to 56,500 points, while the blue-chip Top-40 index increased 0.48% to 50,452 points.
Leading the blue chips was luxury brand Richemont ,which gained 5.57% to 112.74 rand, while mining company GoldFields climbed 5.010% to 71.46 rand on the back of anear three-month gold price peak. On the downside, banking stocks took a hit slipping 3.83% to94.45 rand. Standard Bank shed 4.21% to 193.97 rand,while Absa fell 4.210% to 165.99 rand.
The weak GDP numbers weighed quite heavily on the banks,although the heavyweights were up, said Michele Sanpangelo, aportfolio manager at Independent Securities.
"It's definitely a tale of two sectors; ones that like theweak rand and ones that don't," Sanpangelo said.
(Reporting by Olivia Kumwenda-Mtambo and Onke Ngcuka; Editingby Catherine Evans)