A new study has found there is "no significant difference" between the bactericidal effects of plain soap and antibacterial soap.

Antibacterial hand soaps containing the chemical triclosan are not much better at killing germs than regular suds, researchers say.

Triclosan is one of the commonest ingredients in antibacterial soaps, which are used by millions of people and generate $US1 billion ($A1.40 billion) in sales annually in the United States alone.

But studies have linked it to antibiotic resistance and hormone problems, prompting a safety review by the US Food and Drug Administration.

Now a study in the Journal of Antimicrobial Chemotherapy reports that when it comes to normal hand-washing, there is "no significant difference" between the bactericidal effects of plain soap and antibacterial soap.

Triclosan only became effective after microbes had been steeped in the soap for nine hours, the authors found.

"At times less than six hours there was little difference between the two (soaps)," the researchers wrote of their tests.

For all the tests, the team used antibacterial soap containing 0.3 per cent triclosan - the maximum allowed in the European Union, Canada, Australia, China and Japan - said study co-author Min Suk Rhee of Korea University.

The researchers said consumers need to be aware that antibacterial soaps do not guarantee germ protection.

"It should be banned to exaggerate the effectiveness of... products which can confuse consumers," said Min.

Several soapmakers have already stopped using triclosan, he added.