Global watchdog Human Rights Watch on Thursday urged Zimbabwe to take urgent steps to stem child labour and other rights abuses on the country's tobacco farms.In a report titled "Bitter Harvest", the HRW revealed that children as young as 11 were working on tobacco farms, often in hazardous conditions, to earn school fees or supplement the family income.Workers were exposed to nicotine and toxic pesticides and suffer symptoms consistent with poisoning such as nausea and vomiting, it said."Zimbabwe's government needs to take urgent steps to protect tobacco workers," said Margaret Wurth, co-author of the Human Rights Watch report.Of the 125 people interviewed, one 12 year-old girl described how she fell ill after handling an unnamed pesticide."We carry the knapsack and start to spray," the girl named Mercy is quoted as saying. "I feel like vomiting because the chemical smells very bad."A schoolteacher said his pupils sometimes miss class as they go to work on the tobacco farms."From the onset of the tobacco growing season these children start being absent," said the teacher named only as Joseph from the northern Mashonaland west province."You find out of 63 days of the term, a child is coming 15 to 24 days only," he said.Davidzo, a 15-year-old boy in Mashonaland Central, missed 15 days of class to work in tobacco farming. When he returned to school, he was punished by his teachers."I was beaten.... I was so disappointed because I was trying to make an effort to work to raise my school fees. I thought I was doing good for myself," he said.Seasonal workers on some large-scale farms said they were pushed to work excessive hours without overtime and forced to go weeks or months without pay.Tobacco's importance to Zimbabwe's economy cannot be underestimated, it is the largest foreign currency earner after gold.KEEP UPDATED on the latest news from around the continent by subscribing to our FREE newsletter, Hello Africa.FOLLOW News24 Africa on Twitter and Facebook. Last year the country realised $900m from tobacco exports mainly to China and Indonesia, according to the tobacco industry's marketing board.Human Rights Watch called on the government to investigate and monitor child labour and human rights violations on tobacco farms.President Emmerson Mnangagwa, who took charge after long-time ruler Robert Mugabe was forced to step down, has pledged to prioritise agriculture as he looks to revive Zimbabwe's moribund economy.