Washington, June 14: US Defense Secretary Robert Gates has said that the Obama administration was disappointed by the unexplained failure of recent raids on two militant compounds in Pakistan's tribal areas.

Gates said that the Central Intelligence Agency (CIA) had shared intelligence about the compounds with Pakistan in the past several weeks to restore relations with the South Asian country.

However, when Pakistani forces raided the facilities, used for the manufacture of improvised explosive devices, the militants had disappeared.

The "IED factories" were located in Pakistan's North and South Waziristan region.

The Defense Secretary insisted that he was not certain how or why the effort went awry.

"There was clearly disappointment on our part," The Dawn quoted Gates, as saying.

It has been reported that Pakistan's intelligence service, Inter-Services Intelligence (ISI), had tipped off the militants.

Earlier, CIA Director Leon Panetta, during his visit to Islamabad, had confronted Pakistan Army chief General Ashfaq Pervaiz Kayani and ISI Director-General Ahmed Shuja Pasha with evidence of collusion between pro-Afghan Taliban militants and Pakistani security officials.

Panetta reportedly shared with Kayani and Pasha a 10-minute edited video that shows the militants evacuating the bomb factories.

The CIA chief alleged that the militants were tipped off within 24 hours of the US sharing information on the facilities with the Pakistanis. (ANI)