The US economy, which is hit by one of the worst crisis after the Great Depression, is coming back stronger and faster than predicted, the US Treasury Secretary, Timothy Geithner, has said.

"The economy is gradually, but definitely, getting stronger. We are coming back, and we are coming back faster and stronger than most people predicted – faster and stronger than Europe and Japan. It is going to take more work, though," Geithner said in his address to the United Steelworks Headquarters in Pittsburgh, Pennsylvania.

"We need to do more now to help businesses expand investment and put people back to work. We need to help small businesses get credit. We need to rebuild America's infrastructure. We need to help states and cities keep teachers in the classrooms and police on the streets. We need to expand exports. And we need to encourage innovation," he said.

Noting that this is still a very tough economy, Geithner said the US was hit by the worst global financial crisis since the Great Depression of the early 20th century.

"It's tough because this crisis followed a long period of policy choices, policy neglect, policy mistakes that made us weaker and less secure," he said.