A NATO program designed to boost literacy among Afghan forces is falling short of "unrealistic" goals despite an investment of $200 million, an inspector general said Tuesday in a report.

Coalition commanders are unable to fully measure the results of the literacy effort as there is no independent verification of testing and the recruits are not tracked as they move to different units, according to John Sopko, US special inspector general for Afghanistan reconstruction.

The NATO training mission had set a goal that by the end of this year 100 percent of Afghan army and police forces could meet a basic literacy level, equivalent to first grade at an American elementary school, and 50 percent meet a third grade level.

But only about 64 percent of personnel can pass the basic literary test and only 21 percent can meet the third grade reading level, according to the report.

The objective had been set in 2009, before Afghan National Security Forces (ANSF) expanded from a total of 148,000 troops to about 352,000.

Several officials in the NATO program "told us they do not know how the goal for the literacy program was developed, but that attaining it based on the current authorized ANSF end strength may be 'unrealistic' and 'unattainable,'" the report said.

"Some command officials responsible for the literacy training program roughly estimated that over half of the force was still illiterate as of February 2013," it said.

With the Afghan forces suffering from a high attrition rate of 30 to 50 percent, it has been difficult for the mission to gauge the impact and success of the program, the report said.

The need to deploy troops to battle has meant some recruits are pulled out of literacy classes before they have finished their required 64 hours of instruction, it said.

The NATO literacy training mission says that 224,826 members of the Afghan security force have passed a first-grade literacy level and 73,700 have met the third-grade level. But the accuracy of the numbers cannot be ensured as there is no way to independently determine if the recruits can pass proficiency tests as claimed by contractors teaching the troops, the inspector general said.

Moreover, about 45 percent of police officers recruited between July 2012 and February 2013 "were sent directly to field checkpoints without receiving any literacy training," the report said.

US and NATO officers launched the literacy project after recognizing most Afghan recruits could not read or write, and could not even understand the serial numbers on their rifles.

The commanders see the effort as vital to building up a more effective Afghan army and police force. Soldiers and policemen that can read and count are better able to uphold the law, account for weapons and track their pay, officers say.

Due to decades of war and deprivation, only about a third of the Afghan population can read or write and only 13 percent of recruits to the country's security forces have basic literacy, according to the Afghan ministry of education.

Afghan security forces will be responsible for security across the country after NATO-led combat troops leave as planned at the end of the year.