ABC News' Hamish Macdonald reports:

LONDON - Actress Angelina Jolie opened a high-profile global summit in London today, aimed at ending sexual violence in conflict and emphasizing the message that victims have nothing to be ashamed of.

Rape in war zones is widespread and affects hundreds of thousands of people, many in the Middle East, Africa and Latin America.

"It is a myth that rape is an inevitable part of conflict; there is nothing inevitable about it," Jolie, special envoy to the U.N. Commissioner for Refugees, said in opening the London conference. "It is a weapon of war aimed at civilians. It has nothing to do with sex, everything to do with power."

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Addressing the End Sexual Violence in Conflict Global Summit to loud cheers, the actress said the gathering could be a turning point. "We must send a message around the world that there is no disgrace in being a survivor of sexual violence, that the shame is on the aggressor," she said.

U.K. government organizers hope the meeting of more than 140 countries will result in, among other things, new standards for documenting and investigating sexual violence in all war zones. Jolie also wants the four-day event to push for training of armies in preventing sexual violence. "We need all armies, peace-keeping troops and police forces to have the prevention of sexual violence in conflict as part of their training," she said.

British Foreign Secretary William Hague will be joined later this week by U.S. Secretary of State John Kerry at the summit. They are pushing for greater awareness of the issue.

"This is one of the great mass crimes of the 20th century and the 21st century," Hague told the BBC. "If anything, this is getting worse; war zone rape as a weapon of war, used systematically and deliberately against civilian populations."

Delegates are attending this conference from around the world hoping to break the relative silence on the issue.

"This whole subject has been taboo for far too long," Jolie said. "War zone rape is a crime that thrives on silence and denial. The stigma harms survivors and causes feelings of shame and worthlessness."

(Photo Credit: Eamonn McCormack/WireImage/Getty Images)