WASHINGTON: US House Speaker Nancy Pelosi, a key ally of President Barack Obama, has come under fire over whether she has long known about harsh interrogation tactics used in George W. Bush's "war on terror."

"She was briefed on it and if she felt it was wrong she should have acted," Senator John McCain, the losing 2008 Republican presidential nominee, told reporters on Tuesday.

Most of the criticism has focused on why, if briefed, Pelosi did not do more to stop the use of waterboarding, or simulated drowning, a technique many say amounts to torture.