The United States has praised Pakistan President Pervez Musharraf [Images] for his role in the war on terror, but said that Islamabad had not been successful in closing down the terror network in restive tribal areas on the Afghan border.

"Now, in those tribal areas, they made some efforts. Thus far, they have not been successful in closing down these terrorist networks and those who are supporting them," US Assisstant Secretary of State Sean McCormack said.

"That's going to require a concerted effort. And we're going to continue to work with the Pakistani government to see that there is not a safe haven from where terrorist groups can operate," he said in a briefing.

Lauding Islamabad for its efforts to combat terrorists, McCormack said: "They have worked closely with us to set Pakistan on a different course. President Musharraf has decided that himself and we have tried to be supportive of that."

Pakistan had "launched numerous operations to try to disrupt terrorist attacks as well as break up terrorist cells", he said adding, "there was an issue of Al Qaeda [Images] and Taliban sympathisers operating in the tribal regions in its north-west.

The prime minister (Shaukat Aziz) and his government are very much aware that it's a problem. We've seen the kind of violence that potentially can emanate from those regions and it is directed at us, it's directed at the Afghan populations. It's directed at Pakistani populations. So they understand very well what the threat is," McCormack added.