BEIJING - China Financial Futures Exchange (CFFEX) announced on Wednesday it will raise the margin requirements for sell orders on CSI 500 index futures to curb speculation.

Traders must pay margin requirements equivalent to 20 percent of the contract value starting from Wednesday's clearing, up from the previous 10 percent.

The margin requirement will be further elevated to 30 percent from Thursday.

The CFFEX said Monday night that it would limit investors' daily purchases of CSI 500 index futures to 1,200 lots for rise and fall.

The CSI 500 index comprises the 500 largest companies listed in the Shanghai and Shenzhen security markets.