WASHINGTON (AP) -- Federal Reserve Chair Janet Yellen is stressing the need to review the unconventional monetary policies that central banks around the world deployed in response to the 2008 global financial crisis.

She said Thursday that the post-crisis period offers policymakers an opportunity to assess the effectiveness of the tools and better understand the impact of new regulation.

"Policymakers have to carefully weigh the advantages and disadvantages of alternative monetary implementation frameworks in the presence of new policy tools," Yellen said in remarks at a two-day research conference sponsored by the Fed.

Policymakers should also be "mindful of new channels for monetary policy transmission that may have emerged from the intricate economic and financial linkages in our global economy that were revealed by the crisis," she said.

In her brief remarks, Yellen did not address current economic conditions or future policy moves by the Fed.