A "staggering" number of children across the globe do not attend school, presenting a large challenge to the United Nation's goals to educate all children by 2030, reported the UN's cultural agency on Friday.

"Our focus must be on inclusion from the earliest age and right through the learning cycle, on policies that address the barriers at every stage, with special attention to girls who still face the greatest disadvantage," said UNESCO's Director General Irina Bokova in a statement.

Although around 263 million children are currently not in school, the figures show a marked improvement from 2000 when some 374 million children were not in school.

The highest number of children without access to education are living in sub-Saharan Africa, according to the new report. The region also has the highest rate of exclusion with 21 percent of primary school age children (ages 6 to 12) denied access to education.

The reasons for such high rates include gender inequality and poverty, UNESCO said.

Overall, girls are more frequently shut out of education globally. An estimated 15 million girls of primary school age will never attend school, compared to 10 million boys, according to the report.

The agency noted that armed conflicts across the globe present a major barrier to children getting better access to education. Around 22 million primary school-age children who are not in school live in conflict-ridden areas.

Last year, the UN adopted a set of global goals for 2030 which included providing children around the world with complete primary and secondary school.

"These new findings show the hard work ahead if we are to reach this goal," Bokova said.

UNESCO also noted that many countries do not make secondary school compulsory, with many older children deemed ready to work.

rs/jm (Reuters, epd)