Updated 2:00 PM ET
(CBS News) KABUL - A major terrorist plot targeting Afghan soldiers was uncovered Monday at the Ministry of Defense headquarters in Kabul, an official at the Ministry has confirmed to CBS News.
The official, who asked not to be identified because the Afghan government yet to acknowledge the plot, revealed that 11 suicide vests were found in three rooms in the area surrounding a parking lot at the Ministry.
The investigation is still in its early stages but it is known that 11 buses were scheduled to leave the parking lot carrying Afghan army personnel. The working theory among investigators so far is that a bomber was meant to get on each of those buses and stage a spectacular simultaneous attack.
Six Afghan soldiers were immediately arrested on the scene and it is believed they were ready to proceed with a suicide attack.
The BBC reports Tuesday that 12 additional arrests have been made.
The Afghan government has so far refused to confirm the plot, but CBS News has learned that Afghanistan's defense minister has been called to the presidential palace to give a full briefing on the details of the investigation. The palace itself is less than a mile away from where the vests were found.
However, Afghan officials later said the intelligence report was false, The Associated Press reported.
The plot was uncovered in Kabul on a day whenby members of the Afghan security forces - incidents the U.S. military has labeled "Green on Blue" attacks.
The attacks - and the discovery of the suicide vests - highlight an ongoing problem of Taliban infiltration of the Afghan security forces, along with a series of incidents where personal conflicts have escalated to violence.
In February, a U.S. Army Colonel and a Major were killed inside the Ministry of the Interior by a gunman believed to have been an Afghan policeman who escaped and remains at large.