The market regulator is considering action against five high-frequency traders and one dark-pool operator as its taskforce continues to consider new rules for those practices.

Staff from the Australian Securities & Investments Commission have been working closely with market players on "problematic algorithms" used by computer-driven high-frequency traders. Five matters have been referred to enforcement, according to the latest market supervision report.

ASIC said problematic algorithms and the effects of high-frequency trading continued to be of concern.

"In particular, wash trades (which occur when one account executes both sides of the trade) are a significant obstacle in maintaining fair and orderly markets," ASIC said.

It has also referred one matter relating to dark-pool trading -- off-market exchanges operated by brokers and others to trade shares -- to its enforcement division for investigation.