WASHINGTON (AFP) – An increasing number of Americans have real concerns about the safety of atomic power after a massive earthquake and tsunami sparked fears of a catastrophic meltdown at a Japanese nuclear plant, a poll released Thursday showed.

In a USA Today/Gallup poll conducted since the disaster, some 70 percent of respondents said they were worried about nuclear energy, up significantly from the 57 percent who expressed similar concerns just two weeks ago.

According to the poll, 47 percent of Americans oppose building more nuclear plants with only 44 percent in support. The rest did not have a strong opinion on the issue.

Japanese authorities were struggling to control three nuclear power plants damaged by Friday's earthquake and subsequent tsunami as the United States recommended its citizens stay more than 50 miles (80 kilometers) away.

US lawmakers are also struggling with the safety issue, questioning administration officials over the possibility of a similar accident in the US.

President Barack Obama has sought increased funding for nuclear power as part of a push to move the country away from fossil fuels.

Energy Secretary Steven Chu said Wednesday that was still the administration's position.

Nuclear energy "has an important role to play in our energy portfolio," Chu told lawmakers, noting that the president's budget asks Congress for $36 billion in loan guarantee authority to "jump-start the domestic nuclear industry."

The US nuclear industry has largely stalled, with no new plants built to completion since the March 28, 1979 accident at Three Mile Island, a partial reactor meltdown that led to "very small" releases of radioactivity, according to the US Nuclear Regulatory Commission (NRC).

No one was killed and no immediate injuries were linked to the incident, but it stirred an outcry that blocked further expansion of the US nuclear program.

An attempted nuclear renaissance in the United States has faltered due to the heavy costs associated with reactor construction, which the Obama administration hopes can be overcome through government-backed loan guarantees.

The poll of 1,004 adults had a margin of error of four percentage points.