She is the star of Hollywood blockbusters - but Angelina Jolie's most lasting legacy could be her real life role as a "fierce and fearless advocate", US secretary of state John Kerry said.

His words come on the final day of the global summit to End Sexual Violence in Conflict (ESVC), which Jolie has described as "an emotional experience".

The film star arrived at the ExCel exhibition centre in London's Docklands hand-in-hand with her partner Brad Pitt and said she will continue to focus on the issue "through art" and "work on the field".

Jolie and Foreign Secretary William Hague have launched an international protocol which they hope will "shatter the culture of impunity".

So far, 155 countries have endorsed the declaration of commitment to end sexual violence in conflict.

Mr Kerry hailed the efforts of the Tomb Raider star and the Conservative politician.

He described Jolie, who is special envoy for the UN High Commissioner for Refugees, as a "fierce and fearless advocate".

"We've all watched her play many remarkable roles, but perhaps her most lasting legacy actually comes from a role she plays in real life - and that is the role of fierce and fearless advocate," he said.

Jolie said one of the "most heartening" aspects of the summit has been seeing so many of the world's male leaders "prepared to confront the taboos" surrounding the subject.

"I believe that one of the outcomes of this summit is that this subject is now firmly on the top table of international diplomacy.

"And we will work to ensure that it stays there," she said.

Jolie said she will work with Mr Hague and others for "as long as it takes" to prevail in the struggle of sexual violence in conflict.

She said the work begun at the summit is "very, very much linked" with violence against women in other contexts, such as the kidnap of the schoolgirls in Nigeria or the recent rape cases in India and Pakistan.

Speaking about Mr Hague, who he pointed out has travelled extensively and met those affected by sexual violence, Mr Kerry said: "He has not just seen these unspeakable horrors, but he refuses to stay silent.

"That, my friends, is leadership."

In her speech, Oscar winner Jolie said: "For me, and I suspect for many of you, this summit has been an emotional experience.

"We have all come together based on a common desire to end war zone sexual violence, and we have mapped out every area of action we need to take."

The actress said there is "no doubt" that after these four days it is now known what has to be done.

Mr Hague described the last three days as "remarkable", and said the summit has "opened the eyes of the world to this issue".

In a closing speech, Mr Hague said of the four-day event: "I hope it is a moment we will look back on and say this was where we started to tip the tipping point, this was where we started to turn the tide, this was where we demonstrated to millions of people that it is possible to succeed in defeating and ending sexual violence in conflict."

A film Jolie made - In The Land of Blood and Honey - was what brought her and Mr Hague together, leading them to co-chair the ESVC summit at the east London venue.

Jolie said she was "very moved" that the 2011 film, which is set in Bosnia during the conflict, was responded to by Mr Hague.