Negroponte met political leaders to evaluate progress towards peace during a two-day trip. He is the most senior U.S. official to visit the country since it was divided by a 2002-2003 civil war in which rebels seized its northern half.

"I urged Ivorian leaders from across the spectrum to take the steps they know are necessary to implement the agreement and to work together to improve Cote d'Ivoire's prospects for the future," he told reporters at the main airport in Abidjan.

The April deal followed direct talks between President Laurent Gbagbo and rebel leader Guillaume Soro, now prime minister, and brought high hopes of reconciliation after a string of failed foreign-imposed deals.

But diplomats have voiced concern over the slow pace of implementation. There has been little movement on key steps such as disarmament and reunification, although there is no apparent disagreement between the sides on how to proceed.

Some politicians said this week that a crucial voter identification scheme -- meant to ensure Ivorians with the right to vote have the legal documents enabling them to do so -- could not be accelerated because of a lack of funds.

"I don't think any of the obstacles that were mentioned were insuperable. I think the important thing is the commitments of everyone to overcome these challenges as quickly as possible," Negroponte said.

He said the resource-rich country's 2006 bilateral trade with the U.S. was around $1 billion, though Ivory Coast was removed from the U.S.'s AGOA preferential trade scheme in 2005, after days of rioting aimed at French and other expatriates.

"I think that if the terms of the (peace deal) are fulfilled and democratic elections take place in the near future, that will also create ... the conditions for even more expansive collaboration between the United States and Cote d'Ivoire," he said.

Negroponte is due to travel to Nigeria, Burkina Faso and Mali after Ivory Coast.