The United Nations in Afghanistan said there was "no credible justification" in keeping girls out of high schools and there was "no parallel anywhere in the world."
The United Nations missions in Afghanistan (UNAMA) issued a statement on Sunday, saying the Taliban had opened schools for boys on this day last year, but "instructed girls to remain at home."
UNAMA issued a statement to mark a full year of closure of secondary schools for girls in Afghanistan, saying the Taliban had failed to deliver on various promises to enable girls to return to classrooms.
"This is a tragic, shameful, and entirely avoidable anniversary," said Markus Potzel, the acting head of UNAMA.
Will the Taliban allow girls to go to schools?
The Taliban officially banned secondary education for girls after taking power last year, but some schools quietly opened in recent weeks.
The AFP news agency reported that girls were seen wearing hijabs and heading to schools earlier this month in some provinces, even though they were told there was no change in the official education policy.
The Taliban then reportedly closed those schools, with local media footage showing girls in Afghanistan's eastern Paktia province protesting against the Taliban's decision just a few days ago.
Afghans are now watching closely to see whether the Taliban will allow girls to attend schools.
In the two decades between Taliban administrations in Afghanistan, girls were allowed to go to schools and women were allowed to work.
Girls belong in schools, says UN chief
Several Taliban officials say that the ban on schooling for girls is only temporary but they are yet to enact any change in official policy. They have also not provided any time frame for opening schools.
The hardline Islamist group have made a number of excuses for keeping schools closed, from saying they needed more funding to saying they needed more time to restructure the school syllabus.
The UN Secretary-General Antonia Guterres on Sunday tweeted it was "a year of lost knowledge and opportunity that they will never get back."
"Girls belong in school. The Taliban must let them in," Guterres said.