The United Nations chief says the coronavirus pandemic has led to the largest disruption of education in history, with schools closed in more than 160 countries in mid-July affecting more than one billion students.

Axar.az reports citing foreign media that in addition, Secretary-General Antonio Guterres said Tuesday that at least 40 million children worldwide have missed out on education “in their critical pre-school year.”

As a result, he warned that the world faces “a generational catastrophe that could waste untold human potential, undermine decades of progress, and exacerbate entrenched inequalities.”

“We are at a defining moment for the world’s children and young people,” Guterres said in a video message and a 26-page policy briefing.

“The decisions that governments and partners take now will have a lasting impact on hundreds of millions of young people, and on the development prospects of countries for decades to come.”

Guterres called for the reopening of schools once the local transmission of the virus is under control.