UNESCO warned on Tuesday of a global crisis of teacher shortages and stressed that 69 million teachers are needed worldwide to provide universal primary education by 2030.

In a statement released to mark World Teachers' Day, celebrated this Wednesday, October 5, the United Nations Educational, Scientific and Cultural Organization (UNESCO) called on governments to step up their support for the teaching sector, given the "difficulties" in "retaining their staff and attracting new talent."

The greatest teacher shortage, according to the UN agency, is in sub-Saharan Africa, which has "some of the most overcrowded classrooms in the world," the "most overworked teachers," and "understaffed" education systems.

"Lack of training, unattractive working conditions and inadequate funding are all factors undermining the profession and exacerbating the global apprenticeship crisis," Audrey Azoulay, the organization's director-general, said in the same released statement.

UNESCO projections indicate that to achieve the universal basic education goal of Agenda 2030, 24.4 million more teachers are needed for primary education and 44.4 million more for the next level.

In Sub-Saharan Africa, the needs for primary education are 5.4 million teachers and for secondary education, with 90 % of its schools facing a severe teacher shortage, 11.1 million.

The region with the second largest deficit is South Asia, where 1.7 million additional primary school teachers and 5.3 million additional supplementary school teachers will be needed to meet the target.

Among the aspects that require improvement, UNESCO pointed out the improvement of conditions for teachers, especially with regard to workload.

In low-income countries, each elementary school teacher has an average of 52 students per class, while the world average is 26.

UNESCO also called for better training for teachers and alluded to the necessary care for the environment where they live in the most disadvantaged and remote areas, especially in the case of female teachers.

The crisis in the profession is also accentuated by uncompetitive salaries.

UNESCO data indicate that six out of 10 countries pay primary teachers less than other professionals with similar qualifications, and that the gap is widest in the most developed nations.

"Only three high-income countries have a commendable teacher pay policy: Singapore, with an average salary equal to 139 % of comparable occupations, Spain (125 %) and South Korea (124 %)," the UN agency added.