Washington, Apr 2 (IANS): The Central Intelligence Agency has admitted to accidentally leaving "explosive training material" under the hood of a Northern Virginia school bus for more than a week last month.

The agency inadvertently left an unknown quantity of the explosive under the hood of a Loudoun County Public Schools bus after using the vehicle in a training programme last week, The Guardian reported.

According to a statement released by the CIA, "explosive training material was inadvertently left by the CIA K-9 unit in one of the buses used in the exercise."

The school district confirmed that the bus made eight runs on March 28 and 29, carrying 26 public school students to three different schools for a total of 145 miles of travel.

The explosive material remained apparently undetected till the bus underwent routine maintenance performed by the school district on Wednesday.

"The CIA assured Loudoun officials the training material used in this exercise is stable and posed no danger to students on board the bus," Loudoun County Public Schools said in a statement.

"The exact nature of the training material used in this exercise is not being released at the request of the CIA so as not to compromise its training techniques."

The material, characterised as "stable" by the CIA and "benign" by the school district, was characterised by a district spokesperson as a "putty-type" explosive requiring the use of a detonator.

A container holding the material was placed in the engine block of the bus as part of the training exercise, according to the CIA.

At some point, however, a portion of the explosive material fell from the container into the engine compartment and was not recovered till it was discovered by a district mechanic.

In response to the incident, the CIA announced that the K-9 training programme has been suspended till inventory control and procedural standards undergo review.

"CIA has taken immediate steps to strengthen inventory and control procedures in its K-9 program," the agency said.

"CIA will also conduct a thorough and independent review of its K-9 training programme. CIA performed a full inventory this morning and accounted for all the explosive training material used in the programme."