JOHANNESBURG, Aug 18 (Reuters) - South Africa's Johannesburg Stock Exchange failed to open equity market trading as usual at 9 a.m. (0700 GMT) on Wednesday as record high trading volumes the previous day snapped its systems, the company said.

It said in a statement continuous trading would begin at 2:30 p.m. (1230 GMT).

The JSE had told traders and brokers before the start of normal trading hours that it was experiencing significant delays with batch processing on its Broker Dealer Accounting system.

The high trading volumes on Tuesday came on the back of a massive sell-off in the shares of index heavyweight Naspers Ltd where investors had to adjust their holding in the company post a share swap with its Amsterdam-listed subsidiary Prosus.

The JSE said its trading volumes topped 145 billion rand ($9.71 billion) on Tuesday, which many traders and investors said was one of the highest recorded on the exchange.

"This has resulted in a delay in the start of trading for the JSE equity market," JSE said in a statement.

Despite the company informing traders before the scheduled opening and providing regular updates, some were critical of the outage.

Wayne McCurrie, portfolio manager at FNB, said: "Yesterday the volumes were exceptionally high on the JSE and you would think there has to be adequate back-up, that there would be another system that they could default to."

He called it "embarrassing" especially as it was not for the first time.

Greg Davies, a trader with Cratos Capital said the delay in trading at Africa's biggest stock exchange would have knock-on effects on the futures market and investors would consider moving to alternative stock markets in the country. ($1 = 14.9259 rand) (Reporting by Promit Mukherjee; Editing by Alexander Winning and Alison Williams)