UN Secretary General António Guterres says he is "appalled" by Wednesday's killing of veteran Palestinian-American Al Jazeera journalist Shireen Abu Aqla.

He also called for an independent investigation into her death.

Abu Aqla, 51, died while covering a raid by Israeli forces in the occupied West Bank. Her producer was injured.

Al Jazeera said Israeli troops "deliberately" shot her. Israel's prime minister said it was "likely" she was shot by Palestinian gunmen.

The prime minister, Naftali Bennett, called for a joint post mortem and investigation with the Palestinians, but on Thursday Palestinian Authority Civil Affairs Minister Hussein al-Sheikh said the request had been refused.

Palestinian Authority President Mahmoud Abbas said he held the Israeli government fully responsible for what he described as a "crime of execution".

In a statement issued via his spokesperson late on Wednesday, Mr Guterres called on "the relevant authorities to carry out an independent and transparent investigation into this incident and ensure that those responsible are held accountable.

"The secretary general condemns all attacks and killings of journalists and stresses that journalists must never be the target of violence," the statement added.

Meanwhile, White House spokeswoman Jen Psaki wrote on Twitter that Americans were "heartbroken to learn of the killing" of Abu Aqla and the injuries to her producer.

"We send our deepest condolences to her family, friends, and strongly condemn her killing," Ms Psaki added, calling her a "reporting legend" who will be "mourned by all who knew her".

Abu Aqla was widely known and widely admired - by viewers and colleagues alike.

Early on Wednesday morning she went to the Jenin refugee camp to report on a raid by Israeli soldiers and security forces, which the Israeli military said was conducted to apprehend "terrorist suspects".

"During the activity, tens of Palestinian gunmen fired at and hurled explosive devices toward the soldiers. The soldiers responded with fire toward the gunmen and hits were identified," a military statement said.

The Palestinian health ministry said Abu Aqla was hit in the head by a live bullet during the raid. She was taken to hospital in a critical condition and later pronounced dead.

Another Palestinian journalist, Al Jazeera producer Ali Samoudi, was shot in the back and was in a stable condition in hospital, the health ministry added.

Al Jazeera cited Mr Samoudi as saying there was "no Palestinian military resistance" at the scene of the shooting.

Shireen Abu Aqla was a household name across the Arab world - literally.

Across the region and beyond, her calm commanding presence filled living rooms, courtyards, and camps.

Living in Jerusalem, I remember her in the scrums of journalists covering a conflict which rarely left the headlines. She was part of our tribe but, her authority and quiet confidence set her apart - her ready smile and infectious laugh drew many to her.

When a story mattered, she was there. Now she is not, and, for so many, a big part of every story she faithfully covered will be missing.

New titles are cascading across social media - trailblazer, symbol, martyr.

But she has only one title which she earned throughout her life - journalist.

Abu Aqla joined Al Jazeera in 1997 and was one of its first field correspondents. She was one of the best known women to become a regular face on TV screens covering the Israeli-Palestinian conflict over the years.

The Palestinian ambassador to the UK, Husam Zomlot, told the BBC's Newsday programme that she was a very close friend.

"She was a household [name] in Palestine, in the region and worldwide for being who she was - a prominent journalist who spent her life covering news, covering Israeli brutality in Palestine," he said.

The Israeli military stepped up raids on Jenin following a wave of attacks by Israeli Arabs and Palestinians on the streets of Israel and the West Bank in recent weeks that has left 17 Israelis and two Ukrainians dead.

Dozens of Palestinians have been killed - including assailants shot dead while carrying out attacks, or militants and civilians killed during Israeli raids and confrontations.

Four of the Palestinians who carried out attacks in Israel came from the Jenin district.