The top U.S. diplomat for Africa has raised concerns with Tanzania about plans to build a road through the Serengeti wildlife reserve.

Environmentalists are worried that the road will affect the migration of animals, such as wildebeest, to game parks in Kenya.

U.S. Assistant Secretary of State Johnnie Carson said Wednesday he has raised the issue with Tanzania's foreign minister and with President Jakaya Kikwete. Carson said they are “clearly aware of the concerns” and know the value of the wildlife and the Serengeti.

The U.S. diplomat said Tanzanian leaders are looking for ways to stimulate the economy, but they have no desire to destroy the famed reserve.

U.S. Secretary of State Hillary Clinton is expected to meet with President Kikwete during a trip to Tanzania next week.

The visit is part of Clinton's three-nation tour of Africa focusing on trade, development and regional security.

She also will travel to Zambia and Ethiopia for talks with the leaders of those countries.