Pakistani education activist and Nobel laureate Malala Yousafzai has warned that as many as 20 million girls may never return to schools even after the global Covid-19 crisis is over, the media reported on Sunday.

Speaking at a side event of the UN General Assembly on Friday, Malala acknowledged that Covid-19 had been "a striking setback to our collective goals", such as educating women, reports Dawn news.

"On education alone, 20 million more girls may never go back to the classroom when this crisis ends (and) the global education funding gap has already increased to $200 billion per year," she said.

Malala, who became of the face of Taliban brutality when she was shot in the head for going to school in the Swat valley, reminded the international community that sustainable global goals, set by the UN five years ago, represented the future for millions of girls who wanted education and were fighting for equality.

Noting that little had been done in the last five years to achieve those goals, she asked the world body, "when are you planning to do the work"?

"When will you commit the necessary funding to give every child 12 years of quality education? When will you prioritise peace and protect refugees? When will you pass policies to cut carbon emissions?" she queried.

According to a UN report released last month, the global coronavirus pandemic has created the largest disruption of education systems in history, affecting nearly 1.6 billion students in more than 190 countries and all continents.

Closures of schools and other learning spaces have impacted 94 per cent of the world's student population, up to 99 per cent in low and lower-middle income countries, it added.