Los Angeles, April 16 (IANS): The Los Angeles Unified School District (LAUSD) has asked Apple for a multi-million-dollar refund, saying it is "extremely dissatisfied" with the implementation of a tablet-based education curriculum the company provided them, public radio station KPCC said.

LAUSD attorney David Holmquist sent a letter to the California-based company on Tuesday threatening legal action in case of a failure to reach a satisfactory agreement on the matter, Efe news agency reported citing the radio station.

In 2013, LAUSD entered into an agreement with Apple to provide iPads to 650,000 students of the district.

Under the agreement, LAUSD paid more than $700 a tablet for iPads loaded with the Instructional Technology Initiative (ITI), a curriculum from Pearson Education that was provided at a cost of approximately $200 a unit.

The ITI was part of a $1.3-billion plan to universalise the use of iPads in the country's second largest district.

"While Apple and Pearson promised a state-of-the-art technological solution for ITI implementation, they have yet to deliver it," Holmquist wrote. "As we approach the end of the school year, the vast majority of students are still unable to access the Pearson curriculum on iPads."

Pearson was sub-contracted by Apple to provide maths and English curriculum for the iPads.

The implementation has previously been criticised for its high cost and failure to replace traditional textbooks.

The US Federal Bureau of Investigation is also investigating whether Apple and Pearson had an unfair advantage in winning the lucrative contract due to their relationship with former schools superintendent John Deasy, who resigned from his post in October.