Dan Roberts

Hillary Clinton has thrown her weight behind political efforts to rein in US surveillance powers in her most forthright criticism yet of the National Security Agency (NSA).

The former secretary of state, who has hitherto largely stayed out of the debate sparked by leaks from NSA whistleblower Edward Snowden, called on Congress to restore constitutional privacy protections weakened after terrorist attacks on the World Trade Centre.

"We are finally taking stock of the laws that we passed after 9/11," she told Fox News interviewer Greta Van Susteren. "We did all of this in an a hurry because we were worried and scared and now we need to take a step back and figure out how we make sure that the balance between liberty and security is right."