Haqqani network, based in Pakistan, US officials say is responsible for the recent attacks on the US Embassy in Kabul.

"We are in the final formal review that has to be undertaken to make a government-wide decision to designate the network as a Foreign Terrorist Organisation," Clinton told reporters at a joint press availability with visiting Egyptian Foreign Minister Mohamed Kamel Amr.

"But remember, we've already designated the key leaders. I did that some time ago to make it clear that the leaders of this organization fell under the Foreign Terrorist designation," she said.

"So we're going to continue to struggle against terrorism, and in particular against those who have taken up safe havens inside Pakistan. We are going to continue to work with our Pakistani counterparts to try to root them out and prevent them from attacking Pakistanis, Americans, Afghans, or anyone else," Clinton said.

The State Department has carried out a number of Executive Order 13224 designations that target, essentially the kingpins of the Haqqani Network – financiers, leadership, as well as some of its most dangerous operatives.

US Chairman of the Joint Chiefs of Staff Admiral Mike Mullen had directly accused Pakistan's intelligence service ISI of supporting the Haqqani network's attack on the US embassy in Kabul.