WASHINGTON — Only one-quarter of Americans are confident the U.S. government is prepared to respond to a nuclear emergency similar to the one in Japan.

But an Associated Press-GfK poll shows that just three in 10 respondents think it is highly likely that such an emergency would occur at a nuclear power plant in the United States.

The poll also shows that 60 percent of Americans now say they oppose building more nuclear power plants. That's up from 48 percent who opposed it in an AP-Stanford University Poll in November 2009.

The poll comes as Japan continues to struggle with a nuclear crisis caused by a March 11 earthquake and tsunami. Officials reported no new problems at the Fukushima nuclear plant after a magnitude-7.4 aftershock rattled the nation's eastern coast Thursday.