Fighting has escalated sharply in recent weeks in eastern Congo, where rebels have seized key towns and are closing in on the city of Goma, the government’s last stronghold in the North Kivu province,

A rebel alliance spearheaded by the ethnic Tutsi-led M23 militia said it had seized the lakeside city of more than 2 million people.

A U.N. official says Congolese rebels and allied Rwandan forces have entered the outskirts of Goma and the airport in the key eastern city is no longer in use.