MOSCOW — One woman said children as young as 10 working in the fields developed red rashes on their stomachs and necks as they harvested tobacco for use in cigarettes made by Philip Morris.
Another migrant laborer working in the tobacco fields in Kazakhstan said a farmer confiscated her identification papers and withheld pay to force her to continue working despite dismal conditions.

Human Rights Watch, the group best known for documenting governmental abuse and war crimes, plans to release a report on Wednesday showing that child and forced labor is widespread on farms that supply a cigarette factory owned by Philip Morris International in Kazakhstan, in Central Asia.

While child labor should be condemned in any setting, the report said, employing children on tobacco farms is particularly hazardous because tobacco field laborers are exposed to high levels of nicotine while doing their jobs.

Only a tiny fraction of Philip Morris’s global tobacco purchases are made in the country, and no tobacco raised on the farms employing child labor went into cheap cigarettes sold outside of former Soviet countries. Philip Morris, after being provided with an advance copy of the report, said it agreed to sweeping changes in its purchasing policies in Kazakhstan.

“Philip Morris International is firmly opposed to child labor,” Peter Nixon, a spokesman, said in a telephone interview from the company’s office in Lausanne, Switzerland.

Although child labor is widespread in agriculture in Central Asia, Human Rights Watch said, the particularly harmful environment on the Kazakh tobacco farms warranted special attention. The report cited conditions it said were dangerous to children and adults alike. Lacking easy access to potable water, for example, laborers had resorted to drinking from irrigation channels contaminated with pesticides, the report said.

The group interviewed 68 tobacco farm employees in one district of Kazakhstan during the harvest last fall, identifying them only by their first names and initials.

All, including the children, were migrant laborers from neighboring Central Asian countries, mostly from impoverished Kyrgyzstan. The report also documented violations of basic farm safety rules, like laborers wearing open-toed shoes while working with sharp hoes.

Human Rights Watch researchers documented 72 instances of children working in the Kazakh tobacco fields, which employ about a thousand migrants each season.

Many are paid on a piecework basis, by the ton of harvested tobacco. The group said this was an inducement for parents to bring their children into the fields at harvest time. Even then, the report said, families made only a few hundred dollars for a half-year of farm work, after covering debts to farmers for board and travel.

“A company like Philip Morris certainly has the resources to put an end to these practices,” Jane Buchanan, a senior Human Rights Watch researcher and the author, said in an interview.

Mr. Nixon, the Philip Morris spokesman, said the company already had policies in place prohibiting purchases from farms that used child labor. Over the years, he said, this policy had reduced abusive practices at Kazakh tobacco farms — an assertion that Human Rights Watch said was supported in its interviews.

All the same, Mr. Nixon said, Philip Morris would step up its efforts to eliminate child labor. The company, he said, was “appreciative” of Human Rights Watch for drawing the continuing abuse to its attention.

But Ms. Buchanan said Philip Morris bore moral responsibility for the fate of child laborers in Kazakhstan, even though it was not their direct employer, citing precedents established by apparel and athletic shoe companies that over the last decade had demanded Asian suppliers prohibit child labor.

“Companies are supposed to have policies to recognize and rectify problems with human rights in their supply chain,” she said.

That many of the children worked alongside their migrant-laborer parents during the harvest, she said, did not diminish Philip Morris’s responsibility for their safety.