The coronavirus pandemic has put millions of children at risk of being pushed into underage labor, reversing two decades of work to combat the practice and potentially marking the first rise in child labor since 2000, the United Nations warned on Friday.

As the pandemic pummels the global economy, pushing millions of people into poverty, families may be under pressure to put their children to work for survival, the U.N. said, marking the World Day Against Child Labor.

“As the pandemic wreaks havoc on family incomes, without support, many could resort to child labour,” said Guy Ryder, director-general of the International Labour Organization (ILO), a U.N. agency, in a statement.

“Social protection is vital in times of crisis, as it provides assistance to those who are most vulnerable.”

Due to global shutdowns, the world economy is forecast to shrink 3.2% this year, according to a Reuters poll of more than 250 economists.

Forecasts for global economic growth had tended to range from 2.3% to 3.6% before the pandemic struck.

The number of child laborers worldwide has dropped significantly to 152 million children from 246 million in 2000, according to the ILO.

To prevent a rise in exploitation, the U.N. called upon governments to integrate child labor concerns into broader pieces of legislation, including policy on education, labor markets and human rights protections.

Some countries have begun to do so.

This month, Brazilian labor authorities launched a national campaign to help combat potential child labor, commissioning a song about child slavery to be written by well-known rappers Emicida and Drik Barbosa.

The recent death of an 8-year-old maid in Pakistan prompted the government to propose legislative changes to make it illegal for children to do domestic work.

Advocates also warn that children are susceptible to being put to work while schools are closed in the effort to stop the spread of coronavirus.

“As poverty rises, schools close and the availability of social services decreases, more children are pushed into the workforce,” said Henrietta Fore, executive director of UNICEF, the U.N. children’s agency.

A nonprofit group in Ethiopia launched a novel way to keep thousands of children reading while school was out of session.

(With input from the agencies)