Washington: Following the interception of Al Qaeda's most serious threat in recent years to target American embassies, US Special Forces have been put on high alert to hit potential targets of the outfit in the Middle East, a media report has said.

US Defence Secretary Chuck Hagel, a few days earlier, had directed some of its special forces deputed overseas to be on alert, and be ready for hitting targets of Al Qaeda in Arabian Peninsula (AQAP). Such a move from the Pentagon came after US intercepted messages from a top AQAP leader to his deputy about an Al Qaeda strike.

The US has temporarily closed embassies and consulates in the Middle East and North African region. Multiple media reports said the US has information that members of the Yemen-based AQAP are in the final stages of planning an unspecified attack. The communications were intercepted between Ayman al-Zawahiri - who is Osama bin Laden's successor - and Nasir al-Wuhayshi, head of Al Qaeda in the Arabian Peninsula.

The intercepted message revealed that Al Qaeda leaders in the Arabian Peninsula were planning one of the most serious plots against American and other Western interests since the September 11, 2001 attacks. "This was significant because it was the big guys talking, and talking about very specific timing for an attack or attacks," an American official was quoted.

"It was a well-planned assault," Bergen said referring to the prison break in Pakistan on July 30. He said this was a "known strategy" of Al Qaeda leader Ayman al-Zawahiri. There were other similar operations in the past two weeks in Iraq and Libya. "Well these prison breaks are obviously a concern for the international community writ large. But that is separate and apart from our concern about this specific threat. But again, prison breaks are very concerning to us, and we'll continue to monitor that as well," State Department spokesperson, Marie Harf said.