UN Security Council Thursday expressed outrage at the recent mass rape and assault of civilians in Democratic Republic of Congo (DRC), urging its government to swiftly investigate the incident and bring the perpetrators to justice.

"Members of the Security Council express their outrage at the recent case of mass rape in eastern DRC," Vitaly Churkin, Security Council President for this month, told reporters after the close-door consultations of the 15-member council.

"Members of the Security Council reiterated their demand that all parties to armed conflict immediately cease completely all forms of sexual violence and all human rights abuses against the civilian population in the DRC -- in particular gender based violence, including rape and other forms of sexual abuse," he said.

Churkin said the council members recalled that it is of the utmost importance that the government of the DRC continues to pursue its efforts to fight impunity, demanding that all possible steps should be taken to prevent such outrage in the future.

At least 154 civilians were raped in 13 villages along a 21- kilometer stretch of road in North Kivu province's Banamukira territory between July 30 and August 2, with the attackers blocking the road and preventing the villagers from reaching outside communications. Many homes were also looted.

The UN Secretary-General Ban Ki-moon also expressed outrage in a statement on Tuesday, announcing that he is immediately dispatching Assistant Secretary-General Atul Khare from the Department of Peacekeeping Operations (DPKO) to the DRC to work with Roger Meece, his special representative in the country.

Ban's Special Representative for Sexual Violence in Conflict, Margot Wallstrom, will lead the UN response, the statement said.

In a video-link news briefing Wednesday, Meece, the top UN envoy in the country, told reporters though the attacks occurred near a base of the UN Organization Stabilization Mission in the DRC (MONUSCO) located in Kabula, the UN personnel had no knowledge of the mass rapes until Aug. 12 -- almost 10 days after they had occurred.

He acknowledged that while MONUSCO has been endeavoring to boost its regular contact with civilians and hold weekly meetings with local authorities regarding the safety of villagers, "none of these actions were enough" to prevent the recent tragedy.

According to the UN Population Fund (UNFPA), more than 9,000 cases of rape were reported last year in North and South Kivu provinces alone. Many more cases are estimated to go unreported.

Voicing "the strongest possible condemnation" of the rapes and attacks, U.S. Ambassador to the UN Susan Rice said the council members had "a disturbing briefing both though what we've learned and what we don't know still".

She told the reporters that the council members await answers from Khare and Wallstrom about the actual sequence of events, the shortcomings in processes and procedures, and steps that can be taken to provide more effective, real time protection to the civilians.

"We need to know why and what mechanisms may be put in place to ensure that this type of horror is not repeated again and again," said Rice.