Washington, Apr. 9 : The United States has expressed concern over reports of Taliban taking new areas under their grip in Pakistan, and has termed the issue of existence of extremist elements in the Federally Administered Tribal Areas (FATA) as `critical'.

Addressing media persons here, the US State Department spokesperson Robert Wood said: "Certainly, in terms of dealing with extremism, extremist elements that are operating on Afghanistan's border, in the FATA, this is a very complex issue."

Wood said the US would continue to support Pakistan to fight against the extremists, despite the fact that there were some differences in opinions between the two countries on certain issues.

"You know, we want to work with Pakistan and we have been working with Pakistan as best we can to support them in their efforts to fight extremists. We're going to continue to do so," he said.

Wood refuted media reports that the ISI chief Lieutenant General Ahmad Shuja Pasha had snubbed the US Special Envoy for Pakistan and Afghanistan Richard Holbrooke and the Chairman of the US Joint Chiefs of Staff, Admiral Michael Mullen, and refused to meet them during their recent visit to Pakistan.

"That was not true. They did meet. And so they were good, very constructive meetings," Wood asserted. (ANI)