* Mass rape of nearly 400 last year may be war crime
* Last month alone 170 more were sexually assaulted
* Sexual violence used as weapons of war in Congo
* Violence used to 'punish' govt supporters, UN report says
By Jonny Hogg
KINSHASA, July 6 (Reuters) - The mass rape of nearly 400 people in eastern Democratic Republic of Congo last year could constitute war crimes and crimes against humanity, the United Nations said in a report on Wednesday.
At least 387 men, women and children were sexually assaulted during the attacks, carried out by Rwandan FDLR rebels and a local Congolese armed group in the Walikale region of North Kivu province between July and August 2010.
Last month the U.N. said as many as 170 women were raped by former rebels who had deserted from the army in South Kivu in eastern Congo where increasingly fragmented armed groups are battling the Congolese army, backed by U.N. peacekeepers, over control of land and mineral resources.
The Walikale rapes last year caused an international outcry but only one person has been prosecuted for their role in the attack, carried out by as many as 200 armed men, the U.N. said.
"The fact that these attacks were planned in advance and carried out in a systematic and targeted way, (means) that they could constitute crimes against humanity and war crimes," it said. The attacks were reportedly carried out to 'punish' civilians for supposedly sympathising with government, it said.
Not enough was being done to bring the perpetrators to justice and end the impunity which is seen as encouraging further attacks, Navi Pillay, the U.N.'s High Commissioner for Human Rights said in a statement.
"The Congolese government has the primary responsibility to protect its own population. However, I am obliged to call on the international community to recognise the persistent insecurity in the region and to better equip MONUSCO to enable it to effectively carry out its protection mandate," she said.
MONUSCO is the U.N.'s 17,000-strong peacekeeping force in the country, whose mandate was renewed last week by the United Nation's Security Council.
Congolese soldiers had refused to deploy in the region after a dispute over control of the lucrative mining trade, the U.N. report said.
Insecurity in the east could be a major electoral threat to President Joseph Kabila in polls later this year. In 2006, he took around 90 percent of the vote in the region, one of the most densely populated in the country. (Editing by Bate Felix and Louise Ireland) (For more Reuters Africa coverage and to have your say on the top issues, visit: http://af.reuters.com/)