WASHINGTON: The US securities regulator on Friday said it would review actions that may "unduly inhibit" trading of certain securities and said it was closely monitoring potential wrongdoing amid recent price volatility in the US stock market.

Securities and Exchange Commission (SEC) officials warned against illegal "manipulative trading activity" and said they were working closely with other regulators to monitor the situation after a wild week of trading during which an army of small investors have driven a dramatic squeeze of Wall Street hedge funds in shares of GameStop Corp and other hot companies.

"The Commission will closely review actions taken by regulated entities that may disadvantage investors or otherwise unduly inhibit their ability to trade certain securities," the SEC said on Friday, following a statement earlier in the week it was monitoring market volatility.

Online broker Robinhood earlier in the week placed disputed trading restrictions on certain shares, drawing ire from lawmakers and scrutiny from regulators. The firm had eased restrictions on Friday.

"Our core market infrastructure has proven resilient under the weight of this week's extraordinary trading volumes. Nevertheless, extreme stock price volatility has the potential to expose investors to rapid and severe losses and undermine market confidence," the SEC said on Friday.