WASHINGTON: The United States on Friday said it continues to work with Islamabad on reopening the Pakistani land routes for Nato supplies but declined to expand on the alliance's suggestion that an invitation to Pakistan for this month's Chicago summit was linked to resumption of supplies.

State Department spokesperson Victoria Nuland said Nato Secretary General Anders Fogh Rasmussen spoke very clearly on the issue earlier in the day in Brussels.

Both US and Nato consider the Pakistani land routes as crucial to transportation of supplies into landlocked Afghanistan, but the routes have closed for almost six months since a Nato war plane killed 24 Pakistani soldiers in a cross-border on the security posts.

The incident enraged Islamabad, a longtime ally in the fight against al Qaeda in the region.

When Ambassador Grossman was in Pakistan, some ten days ago, he had substantive conversations himself with regard to the opening of the land routes.

And then he brought with him an expert team to work with the Pakistani expert team, Nuland said, when asked to comment on the issue.

That team is still in Pakistan. They are continuing to work together on this issue, she added.

“I think Secretary General Rasmussen spoke pretty clearly where Nato is on this set of issues. He did remind that the supply routes are blocked and that we are continuing our dialogue and that we are looking for a solution. So I don't think I can improve on that, she remarked.”

Nuland confirmed that the Secretary of State has received a letter from members of Congress urging designating the Afghan Haqqani network as a terrorist organization and said the US administration continues to review the issue.

She added the US and the UN have already designated several leaders of the group as terrorists, which is an effective step.

We are continuing to review the question of the larger group.