US President Donald Trump has accepted US Ambassador to the UN Nikki Haley's resignation.

Ambassador Haley discussed her resignation with President Trump when they met at the White House last week, according to Axios.

The resignation has reportedly shocked the Washington Foreign Policy establishment.

Ambassador Haley has been an outspoken critic of the UN's corruption, bias, and inability to deal with human rights crisis around the world. She was also Israel's biggest supporter at the UN.

The ambassador said that her service at the UN "has been the honor of a lifetime."

Haley criticized Trump's rhetoric during the 2016 Presidential Election and endorsed his rival Marco Rubio for the Republican nomination. Her relationship with Trump improved after the election and she was offered the post of Ambassador to the United Nations.

The ambassador has stated that she is unafraid to criticize the president in private meetings with him.

Sources in the White House stated that Trump said Haley would leave at the end of the year and that she would be "taking a break."

Haley stated that she will not run in the next presidential election and that she will be campaigning for Trump's reelection in 2020.

During a live announcement of the resignation, Trump said Ambassador Haley "has been very special to me" and "a fantastic person."

"She is somebody who gets it. She has been at the United Nations from the beginning with us and worked with us," Trump said.

"She told me six months ago, she said: 'You know, maybe at the end of the year I want to take a little time off."

Turning to Haley, Trump said "hopefully you'll be coming back at some point, maybe in a different capacity."

He praised Haley for "knowing all the players" at the UN. "She got to know China, Russia, India. She knows everybody on a first name basis and they like her ... And maybe more importantly, they respect her."

Haley pointed to her accomplishments over the last to years. "Now, the United States is respected. Countries may not like what we do, but they respect what we do. They know that if we say we're going to do something, we follow it through."

"We've cut $1.3 billion in the UN's budget. We've made it stronger, we've made it more efficient. South Sudan, we got an arms embargo, which was a long time coming. Three North Korean sanctions packages, which were the largest in a generation, done in a way that we could really work towards denuclearizing North Korea. The Iran deal, bringing attention to the world that every country needs to understand, you can't overlook the all of the bad things that they're doing. You have to see them for the threat that they are.

She drew attention to the relocation of the US embassy in Israel from Tel Aviv to Jerusalem. "I think when you look at the anti-Israel bias and the strength and courage that the president showed in moving the embassy and showing the rest of the world: 'we will put our embassy where we want to put our embassy."

"The US is strong again, and the US is strong in a way that should make all Americans very proud."