The number of Brazilian children aged six and seven who do not know how to read or write has risen by 66 percent during the coronavirus pandemic, a report found Tuesday.

The report, by charitable group Todos Pela Educacao (All for Education), found the number of illiterate six- and seven-year-olds in Brazil rose from 1.4 million in 2019 to 2.4 million last year.

That represents 40.8 percent of children in that age group -- a worrying sign for a country that has been hit particularly hard by Covid-19, with widespread school closures that have been particularly detrimental for the poor.

In this file photo taken on November 03, 2019 Google CEO Sundar Pichai and his wife Anjali Pichai arrive for the 8th annual Breakthrough Prize awards ceremony at NASA Ames Research Center in Mountain View, California
In this file photo taken on November 03, 2019 Google CEO Sundar Pichai and his wife Anjali Pichai arrive for the 8th annual Breakthrough Prize awards ceremony at NASA Ames Research Center in Mountain View, California AFP / JOSH EDELSON

It was the largest percentage since record-keeping on childhood illiteracy in Brazil began in 2012.

The group called the increase "worrying," saying early illiteracy raises the risk such children will drop out of school in the future.

"We urgently need substantial policies to help children catch up," said the group's education policy specialist, Gabriel Correa.

"Backsliding on literacy is unacceptable."