At least one-third of the world's children could not access remote learning when Covid-19 shuttered schools.
For over 463 million children, "there was no such thing as remote learning," a new Unicef report revealed.
They lack the equipment, electronic access that would allow them to pursue distance education.
"The sheer number of children whose education was completely disrupted for months on end is a global education emergency. The repercussions could be felt in economies and societies for decades to come," Unicef Executive Director Henrietta Fore said in a statement.
Also, the Unicef report published on Thursday highlighted the gaping geographical differences in children's access to distance education, with the ones in sub-Saharan Africa the most affected.
However, the highest number of children, at least 147 million, who could not access remote learning were from South Asia, according to the Unicef report.
The report used a globally representative analysis on the availability of home-based technology and tools needed for remote learning – access to television, radio and internet, and the availability of curricula delivered by the platforms.
Youngest schoolchildren in poorest households, rural areas were hit hardest during school closures.
They are also most likely to miss out on remote learning during critical years, largely due to challenges and limitations to online learning for them and lack of assets at home, the report said.
Unicef has warned that the situation is likely to be far worse as even where technology and tools exist at home, children may not be able to learn due to pressures to do chores or work.
Globally, 72 percent of schoolchildren unable to access remote learning live in their countries' poorest households, it said.
Also, the UN agency called for urgent investment to bridge the digital divide.
It called on governments to safely reopen schools, expand access to distance learning and arrange for "compensatory learning for lost instructional time."