Rwanda's military last month arrested four top army officers and placed them under house arrest for alleged illegal business dealings in the Democratic Republic of Congo.

The army said the three and a colonel were under investigation for "acts of indiscipline." It said the four men were suspected of taking part in business deals with civilians across the border.

The United Nations had in the past accused Rwanda of smuggling materials such as tin from the DRC.

The DRC government has little control over mines in the country's volatile eastern provinces, near the Rwandan border.

Among the officers arrested is Rwanda's military intelligence chief, Brigadier General Richard Rutatina.