(Recasts headline and lead, changes byline and dateline, and updates throughout)

By Nita Bhalla

NEW DELHI, April 9 (Thomson Reuters Foundation) - Donors' failure to provide promised funds has led to two-thirds of countries missing some targets in a drive to improve education, with 58 million children still out of school and 781 million adults still illiterate, a United Nations agency said on Thursday.

In 2000, 164 countries agreed to try to achieve six key educational goals in the following 15 years, targets that complemented the Millennium Development Goals (MDG) they were also setting.

The key goals included enrolling all children in primary schools, halving adult illiteracy and ensuring that girls had equal access to schooling.

A report by the U.N. educational arm UNESCO, issued on Thursday, said half the countries had failed to enrol all children in primary schools, three-quarters had not halved illiteracy, and more than half had not ended gender disparities at secondary school level.

The report found that Niger, Chad, Pakistan, Nigeria and Ethiopia were among those which were way off target on the six goals, while nations such as Afghanistan, Nepal, Sierra Leone, Rwanda, Tanzania and India were lauded for their efforts.

U.N. officials said while some funds had been wasted, one of the main reasons countries had failed to meet the goals was that rich nations had not lived up to their commitment to provide finances to poorer nations.

"Personally I feel countries that committed themselves haven't delivered and they should, and we need to keep reminding them of that," UNESCO Deputy Director General Getachew Engida told a news conference at the launch of the Education For All (EFA) Global Monitoring report.

"There is no other alternative than simply saying 'Please commit yourself and once you've committed, deliver'. We continue to pass on that message but we haven't been fully successful."

Many countries have increased spending on education. Between 1999 and 2012, 38 countries increased spending by 1 percent or more of national income.

But education is not a priority in many national budgets, and many low-income countries rely on overseas development aid to support their programmes, the report said.

In the first decade after the goals were set, foreign aid for education rose, to $13.9 billion in 2010, but it stagnated because of the global financial crisis and fell back to $12.6 billion over the last two years, U.N. officials said.

The officials did not say what level of support for education had been agreed in 2000.

An extra $22 billion a year - equivalent to 4.5 days of global military spending - is needed to pay for new schools, more teachers and text books to ensure countries reach new education targets now being set for 2030, the report said.

GOOD PROGRESS, BUT NOT ENOUGH

Despite the shortfall in funding, an estimated 34 million more children have attended school since 2000 and almost 70 percent of countries have achieved gender parity at primary school level.

India is one of the handful of countries which has made great strides in education, the report's authors said.

It has reduced the number of children not attending school by more than 90 percent, got all children into primary school and is likely to be the only country in South and West Asia to have an equal number of girls and boys in both primary and secondary school.

Much of the success is due to policies such as the Midday Meal Scheme - the largest school hot meal programme in the world - which gives parents an incentive to enrol their children, as well as the passing of the Right to Education Act, which makes primary education free and compulsory.

By contrast, Nigeria has the highest number of children out of school and one of the world's worst education systems, thanks to a combination of corruption, conflict and lack of investment.

Child rights activists and Nobel Laureate Kailash Satyarthi backed the report's findings that there needed to be more focus on children from marginalised communities, and those living in remote or volatile regions.

Citing militant attacks such as the recent massacre of university students in Kenya, the kidnapping of hundreds of girls in Nigeria and the shooting of pupils in Pakistan, Satyarthi said children wanting to learn were facing grave dangers.

"Education is under attack," Satyarthi told delegates at the launch of the report. "These people can kill children in schools, but they cannot kill education because they know the power of education and ... education is the way to a peaceful and non-violent world."

The Education For All goals are the best indicators of progress towards educational targets set as part of the Millennium Development Goals (MDGs), which also have a 2015 deadline. (Reporting by Nita Bhalla and Emma Batha, Editing by Tim Pearce)