The American ambassador to Kenya says the U.S. will impose travel bans on Kenyan ministers and prominent people who are not backing government reforms aimed at preventing another outbreak of violence.

Michael Ranneberger said Thursday that 15 Kenyans had received letters saying the U.S. was reviewing its relationship with them. He declined to name the individuals.

President Mwai Kibaki and Prime Minister Raila Odinga signed a power sharing deal in February 2008 to end violence over disputed presidential election results that claimed more than 1,000 lives. Public frustration over poverty and corruption fueled the violence.

The power-sharing deal also contained clauses on constitutional, judicial and other reforms, which have not been implemented.