Foreign secretary William Hague will travel with Hollywood actress Angelina Jolie to Africa this week to raise awareness of warzone rape.
Mr Hague and Jolie, a United Nations special envoy, will meet survivors of rape and sexual violence during their visit to the Democratic Republic of Congo and Rwanda, the Foreign Office said.
The pair intend to call on all governments to help eradicate sexual violence in conflicts when they meet local political leaders.
Golden Globe award winner Jolie is continuing the work she started with Mr Hague in London last year, when they launched the UK's Preventing Sexual Violence Initiative.
Her 2011 film In The Land Of Blood And Honey depicted the experiences of women in the infamous rape camps set up during ethnic cleansing in Bosnia-Herzegovina, and was a catalyst for the UK initiative, the Foreign Office said.
Jolie said: ""This visit is about hearing first hand from people who have endured rape and sexual violence during the conflict in the Eastern DRC. We want to identify ways in which the international community can help them to rebuild their lives.
"Unless the world acts, we will always be reacting to atrocities, treating survivors rather than preventing rape in the first place. I welcome the United Kingdom's efforts to galvanise the international action that is so desperately needed."
The actress and mother-of-six has highlighted the plight of refugees worldwide for over a decade in her role as a UN High Commissioner for Refugees Special Envoy.
The visit comes three weeks before the foreign ministers meet in London with their counterparts in the US, France, Canada, Japan, Germany, Russia and Italy for the annual meeting of the G8.
Mr Hague said: "Rape is often used as a weapon of war in conflict zones around the world. It destroys people's lives and communities in the most horrific manner imaginable.
"Yet more often than not the international community looks away, the perpetrators of these brutal crimes walk free and the cycle of injustice and conflict is repeated. We have to shatter this culture of impunity."
Mr Hague and Jolie will urge G8 members to agree landmark measures to secure justice for survivors of sexual violence and deter perpetrators.
These include a new international protocol on the investigation of rape and sexual violence and an agreement that the attacks constitute grave breaches of the Geneva Convention, as well as practical commitments to tackle the violence.
Hague added that meaningful action by governments to tackle sexual violence in conflicts was a "personal priority" of his during next month's meeting.
After the G8, he will take the campaign to the UN Security Council in June and to the UN General Assembly in September.