• People flee as smoke billows after air strikes hit the house of Yemen's former President Ali Abdullah Saleh in Sanaa May 10, 2015. Saleh and his family are safe after airstrikes targeted his residence in the capital Sanaa early on Sunday, a news agency allied to the former Yemeni president said.REUTERS/Mohamed al-Sayagh
  • People stand near the body of a man killed in one of Friday's suicide bomb attacks, at a hospital morgue in Sanaa March 21, 2015. Suicide bombers killed at least 137 worshippers and wounded hundreds more during Friday prayers at two mosques in the Yemeni capital Sanaa, in coordinated attacks claimed by Islamic State.REUTERS/Mohamed al-Sayaghi
  • People carry a body from the rubble of a house destroyed by an air strike at the old quarter of Yemen's capital Sanaa, September 19, 2015. At least ten Yemeni civilians were killed in air strikes by Saudi-led warplanes that targeted this neighborhood, medical sources said on Saturday.REUTERS/Mohamed al-Sayaghi
  • People carry the body of a man they uncovered from under the rubble of a house destroyed by an air strike in Sana'a June 12, 2015.REUTERS/Mohamed al-Sayaghi
  • Walaa Hussien al-Hutroum, 9, sits with her grandmother Safia Ahmed at a hospital where she is being treated for injuries she sustained from an air strike by a Saudi-led coalition, in Sanaa, Yemen April 25, 2015. The girl was hit by shrapnel from a missile that struck a nearby checkpoint on a road she and her family were traveling on as they were fleeing their home in Yemen's northwestern province of Saada a week ago, medics said.REUTERS/Khaled Abdullah
  • Bashar al-Bahri, 12, who was injured by a car bomb attack on a mosque, is helped by a relative at a hospital in Yemen's capital Sanaa June 27, 2015REUTERS/Khaled Abdullah
  • A boy injured in a recent Saudi-led air strike lies on a hospital bed in Yemen's capital Sanaa July 25, 2015. Saudi-led coalition forces announced a humanitarian truce in their campaign against Houthi forces in Yemen would take effect on Sunday evening at 11:59 p.m local time, Saudi state news agency SPA said.REUTERS/Mohamed al-Sayaghi
  • Hamoud Yahya Abdullah, 18, a Houthi fighter injured during recent fighting in Yemen's southern port city of Aden, sits on a hospital bed in the capital Sanaa August 9, 2015. Saudi Arabia and a coalition of other Sunni Muslim states have been fighting since March to restore Yemen's exiled government and to repel the Iran-allied, Shi'ite Houthis, who took control of the capital Sanaa in September.REUTERS/Khaled Abdullah
  • People carry the body of a man killed by an air strike on a Scud missile base in Yemen's capital Sanaa April 20, 2015. The air strike on a Scud missile base in Sanaa caused a big explosion that blew out windows in homes, killing seven civilians and wounding dozens, medical sources told Reuters.REUTERS/Khaled Abdullah
  • A boy shouts slogans as he raises a dagger during a rally against U.S. support to Saudi-led air strikes, in Yemen's capital SanaaREUTERS/Mohamed al-Sayaghi

The United Nations is facing flak from human rights groups for removing the Saudi Arabia-led military coalition from its report that accuses the coalition of being responsible for casualties that resulted from its bombing campaign in Yemen.

"This was one of the most painful and difficult decisions I have had to make." United Nations Secretary General Ban Ki-moon said on Thursday while addressing a press conference in New York. "It is unacceptable for member states to exert undue pressure," Ban added.

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Saudi Arabia is one of the UN's largest donors in the Middle East, giving hundreds of millions of dollars a year to UN food programmes in Syria and Iraq. In 2014, Saudi Arabia gave $500 million — the largest single humanitarian donation to the UN — to help Iraqis displaced by ISIS. Over the past three years, Saudi Arabia has also been become the third-largest donor to the UN's relief agency in Palestine, giving tens of millions of dollars to help rebuild Gaza and assist Palestinian refugees.

According to a report by Reuters, Riyadh had threatened to cut off funding if named by the UN. Reports also suggest the imposition of a Fatwa against the United Nations.

"Children already at risk in Palestine, South Sudan, Syria, Yemen and so many other places would fall further into despair," Ban Ki-moon told reporters.

The report, which was based on the work of UN researchers in Yemen, attributed 60 percent of the 785 children killed and 1,168 injured to the coalition's bombing. 

Meanwhile, according to another report by Reuters, Saudi Arabia has denied using threats. Saudi UN Ambassador Abdallah Al-Mouallimi described the UN figures as "wildly exaggerated."

"It is not in our style, it is not in our genes, it is not in our culture to use threats and intimidation. We have the greatest respect for the United Nations institution," Mouallimi told reporters shortly after Ban spoke.

Attempts at reconciliation are on and the report may be amended pending a joint review by the UN and Saudi Arabia.

UN actions slammed

According to Reuters, a letter to Ban on Wednesday, signed by groups including Human Rights Watch, Amnesty International and Oxfam, criticised the UN chief.

"If the Saudi-led coalition wants to be removed from the list, it should stop killing and maiming children and bombing schools and hospitals in Yemen — the violations for which it was listed," the groups wrote.

"The responsibility of the Saudi-led coalition for grave violations against children in many of these attacks is not in doubt," they added. "The evidence of grave violations against children in Yemen by the Saudi-led Coalition is overwhelming."

The Saudi-led coalition began a military campaign in Yemen in March last year with the aim of preventing Iran-allied Houthi rebels and forces loyal to Yemen's ex-president Ali Abdullah Saleh from taking power.

Some 6,000 people, about half of them civilians, have been killed in Yemen since last March, according to the UN.

The rights groups said Ban's decision to remove the coalition from the UN list undermined "an invaluable tool in efforts to curb violations against children in armed conflict."

"The list creates pressure on parties to armed conflict to comply with international law. Over 20 governments and armed groups have signed UN action plans and taken steps to end violations against children in order to be considered for 'de-listing'," they wrote.

Last year, the United Nations left Israel and the Palestinian militant group Hamas off the blacklist, after they had been included in an earlier draft, but criticised Israel over its 2014 military operations.

Analysts and political commentators believe the unintended consequences of such a decision may hurt the credibility of the United Nations in the long run.