Crowds of Congolese police officers who switched to the M23 rebel group sang and clapped in occupied Bukavu city on Saturday, preparing for retraining under the authority of the Rwandan-backed rebels who are intent on showing they plan to stick around and govern.

DAKAR, Senegal — Rwanda-backed rebels appeared to be heading toward a third major city in eastern Congo, residents said Tuesday, as international pressure rose over the M23's expansion in a mineral-rich region that’s critical for global technology.

The U.N. Security Council unanimously adopted a resolution Friday demanding that the M23 rebels in eastern Congo immediately cease hostilities and withdraw from territories they have seized. The council also threatened sanctions on those who prolong the conflict.