Four election officials taken hostage in eastern Democratic Republic of Congo have been freed after a shoot-out with militiamen, say UN peacekeepers.
Rwanda rebel leader Ignace Murwanashyaka is one of those under UN sanctions
Thirty-two fighters from the Mai-Mai militia were killed, along with two Congolese soldiers but the officials were unharmed, a UN spokesman said.
Elections are due next year under a 2002 deal to end a five-year civil war.
Meanwhile, the UN has released a list of militia leaders and businessmen in DR Congo subject to sanctions.
These include militia leaders in the volatile Ituri region where some 50,000 people have been killed, dissident ex-rebel army commanders, the leaders of Rwandan rebels based in eastern DR Congo and Ugandan and Congolese businessmen accused of selling weapons to the militias in defiance of an arms embargo.
The UN urges all member-states not to grant those named visas and to freeze their assets.
UN SANCTIONS LIST
Ignace Murwanashyaka, Rwandan rebel leader
Sylvestre Mudacumura, Rwandan rebel commander
Laurent Nkunda, Ex-rebel army dissident
Jules Mutebusi, Ex-rebel army dissident
Jerome Kakwavu, Ituri militia leader
Thomas Lubanga, Ituri militia leader
Floribert Njabu, Ituri militia leader
The UN mission in DR Congo (Monuc) said that two Mai-Mai bases had been destroyed in the joint UN-Congolese army operation to free the election officials.
They were seized last month near Virundo, some 220km (140 miles) north of Goma in North Kivu province when they were helping to register voters ahead of next year's elections.
'Crimes against humanity'
Eastern DR Congo remains extremely volatile despite the end of the war elsewhere in the country, with various armed groups, killing, raping and looting.
Earlier this week, the Congolese army, backed up by UN peacekeepers, began an operation to flush Rwandan rebels out of their bases in the vast mountainous Virunga National Park, just north of Goma.
The Rwandan Democratic Liberation Forces (FDLR) rebels had fled there after the 1994 genocide and Rwanda has twice used their presence to justify invading its larger neighbour.
The Congolese army and the UN are trying to restore stability ahead of next year's elections
FDLR leader Ignace Murwanashyaka, currently living in Germany, is on the UN black list, along with his military commander Sylvestre Mudacumura, who is in North Kivu, reports the AFP news agency.
Dissident army commanders Laurent Nkunda and Jules Mutebusi, who seized the town of Bukavu last year, are also subject to sanctions, accused of "crimes against humanity".
General Nkunda is in North Kivu, AFP says, while Colonel Mutebusi is in Rwanda.
In March, several Ituri militia leaders were arrested after years of fighting over the region's gold mines. These have now been put on the UN sanctions list.
Some 15,000 UN troops are in DR Congo to help restore stability and organise elections next year.