LONDON - World powers pledged new measures and funds on Thursday to tackle rape and sexual violence used as a weapon of war, in a "historic" deal drawn up with UN special envoy Angelina Jolie.

G8 foreign ministers meeting in London agreed to commit $35.5 million (27 million euros) to tackle what British Foreign Secretary William Hague likened to slavery as "one of the greatest and most persistent injustices in the world".

Under the new declaration, Hague said rape and sexual violence during conflict would constitute grave breaches of the Geneva Convention, putting a responsibility on signatories to actively seek out and put perpetrators on trial. "I am delighted to announce that today we have reached a historic agreement as G8 foreign ministers: pledging to work together to end sexual violence in conflict," said Hague.

Jolie said that rape in war zones was preventable and urged foreign ministers of some the world's most powerful nations to boost efforts to bring wartime sex offenders to justice.

Speaking in London after a meeting of Group of Eight foreign ministers including US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov, the actress said the world needed to do more to prevent such crimes.

"Hundreds of thousands of women and children have been sexually assaulted, tortured or forced into sexual slavery in the wars of our generation," Jolie said, flanked by eight ministers in suits and Zainab Hawa Bangura, United Nations Special Representative on Sexual Violence in Conflicts.

"Today I believe their voices have been heard and that we finally have some hope to offer them. I welcome the long overdue stand that the G8 has taken," Jolie, a goodwill ambassador for the United Nations High Commissioner for Refugees, said.

"Rape is not a women's issue, or a humanitarian issue, it is a global issue and it belongs here at the top table of international decision-making where he has put it," she said.

Jolie and Hague visited the Democratic Republic of Congo last month to highlight the issue, which Britain has made a priority of its chairmanship of the G8 this year.

In one community in DR Congo, 11 babies between the age of six months and a year old were raped last year, UN special representative Zainab Hawa Bangura told the press conference.

Although Hague conceded that the largest numbers of victims were in Africa - 250,000 women raped in DR Congo over the last decade and hundreds of thousands in the Rwandan genocide - he said tens of thousands had also been abused during the war in Bosnia.

The declaration committed the G8 to work towards a new protocol setting out how to investigate such crimes, provide new training for their militaries on how to deal with sexual violence and provide support for prosecutions in countries worst affected.

Anti-poverty campaign group Oxfam welcomed the new initiative but said promises must be accompanied by the necessary funding to ensure victims receive the protection and justice they deserve. "Much more investment is needed to improve the police, security and justice systems that are designed to protect women and girls, but so often fail to do so," said Oxfam's acting chief, Penny Lawrence.