A lieutenant in the Democratic Republic of Congo army has been arrested for desecrating corpses of rebel fighters, officials have said.

His detention on Thursday evening in eastern DR Congo came a day after the UN chief said he was "deeply concerned" about allegations of such mistreatment.

Ban Ki-moon's spokesman said the UN mission was reviewing its support of those units suspected of involvement.

The army and M23 rebels began fighting near the key city of Goma on Sunday.