The United States on Monday hailed the arrest in France of a key fugitive in the Rwandan genocide as a milestone and pledged to help find others at large.

"This is a milestone for international justice, and a message to all fugitives indicted for genocide that they will be brought to justice," State Department spokeswoman Morgan Ortagus said.

"The United States remains committed to seeking justice for the many men, women and children who were killed," she said.

She said the State Department was offering up to $5 million for information on seven remaining Rwandans wanted for genocide by an international tribunal.

Around 800,000 people -- Tutsis but also moderate Hutus -- were slaughtered over 100 days by ethnic Hutu extremists during the 1994 genocide.