TOKYO (AFP) - Japan said Wednesday it has begun a controversial review of its landmark 1993 apology over wartime sex slavery, a historical legacy that still stokes regional resentment, while stressing that it had no plans to revise the statement.

The landmark apology, known as the Kono statement, acknowledged official complicity in the coercion of women from across Asia into a system of wartime brothels.

Japan's Chief Cabinet Secretary Yoshihide Suga said Wednesday that a "verifying team" would study how the apology was reached and the historical facts it was based on, with their probe expected to be completed later this year.

Mr Suga, the government's top spokesman, told parliament that the "secret team" comprises "five intellectuals" - three women and two men. "We have set up a verifying team which is working to assess" the basis for the statement, Mr Suga told lawmakers.

Under Premier Shinzo Abe's administration, "we will not revise the Kono statement", he added.

The issue of wartime sexual slaves draws particular resentment in neighbouring South Korea. It was unclear what would happen if Tokyo's review was at odds with the official apology, which followed testimony from 16 Korean women about their experiences being forced into prostitution for Japanese Imperial soldiers.

The move comes just over a month after US President Barack Obama, on a regional tour, blasted the forced recruitment into prostitution during World War II as a "terrible, egregious violation of human rights".

The government of the right-leaning Abe announced earlier this year that it would review the apology, sparking protests from Seoul.

While many Japanese accept the country's guilt, some senior politicians on the right - including Mr Abe - have suggested that the issue is overblown, putting a chill on Japan-South Korea relations.

Respected historians say up to 200,000 women, mostly from Korea but also from China, Indonesia, the Philippines and Taiwan, were forced to serve Japanese soldiers during the war.