Highest levels of Pakistan's security apparatus, including the army chief Gen Ashfaq Parvez Kayani, might have been aware of the plot to bomb the Indian embassy in Kabul in July this year, US intelligence and security officials believe, a media report has said.

They also believe that the attack was aided by Pakistan's infamous intelligence agency, ISI.

"It's very difficult to imagine he (Gen Kayani) was not aware," a senior American official told the New York Times.

American intelligence agencies were quoted as saying that senior Pakistani national security officials favour the use of militant groups to preserve Pakistan's influence in the region, as a hedge against India and Afghanistan.

In fact, some analysts believe that ISI operatives did not mind when their role in the July bombing in Kabul became known, the paper added.

"They didn't cover their tracks very well," a senior Defence Department official told the paper, "and I think the embassy bombing was the ISI drawing a line in the sand."