S.African stocks slide to month low, rand softens

* Stocks sink more than 3 percent to 1-month low

* Rand weakens but govt bonds firm slightly

JOHANNESBURG, June 17 (Reuters) - South African stocks sank to a one-month low on Wednesday as weaker metals battered miners, while poorer signals on the economy left the rand a touch lower but still in recent tight ranges against the dollar.

The JSE Top-40 index of blue-chip stocks .JTOPI fell for a fourth session, dropping 3.21 percent, or more than 650 points, to 19,736.69 points, in its biggest one-day percentage fall in two months. The broader All-share index fell 2.96 percent to 21,948.66 points.

"The markets have had a nice run of late, so we're not totally surprised by this pull back, but I think we are a little bit surprised by the voracity of it," said Garth Mackenzie, head of derivatives trading at BOE Private Clients.

"We would have never in our wildest dreams have thought we're going to be down almost 700 points today."

The rand drifted weaker late in the session after Standard & Poor's affirmed its sovereign rating but warned about the financing of a large current account deficit, while bonds inched higher after more poor economic data.

The currency ZAR=D3 traded at 8.11 against the dollar at 1540 GMT, 0.4 percent softer than its last close in New York.

Traders said the unit remained in recent ranges and needed a big move in major currencies to push it in either direction.

"We trawled the bottom for a good couple of weeks without breaking through the 90s (stronger than 7.90 to the dollar), so you would expect a pull back," Rand Merchant Bank dealer Jim Bryson said.

"But we are still in ranges ... we are in the doldrums and need something like the dollar to get us out of it. Any data that has come out has hardly moved us."

S&P affirmed South Africa's ratings but said the outlook remained negative due to the need for big capital inflows to finance its current account shortfall.

The Treasury responded that the rating agency's decision should be seen as positive, given downgrades in other countries.

MINERS BATTERED