A senior US senator has called on President Joe Biden’s administration to push for “a full and transparent investigation” into the killing last month of Al Jazeera journalist Shireen Abu Akleh in a rare move from a Republican Party politician.

Mitt Romney, the senator from Utah, sent a letter on Monday to US Secretary of State Antony Blinken, urging the state department to ensure accountability for Abu Akleh’s killing, which caused global outrage and condemnation.

“We insist that the administration ensure a full and transparent investigation is completed and that justice is served for Ms Akleh’s death,” said the letter, which was co-signed by Senator Jon Ossoff, a Democrat from Georgia.

The progressive wing of the Democratic party has been vocal in calling for an investigation, many of them pointing fingers at Israel for the killing of Abu Akleh, who was a US citizen.

Abu Akleh was shot in the head by Israeli forces in Jenin, in the north of the occupied West Bank, as she covered an Israeli raid on Jenin’s refugee camp on May 11. Al Jazeera said she was “assassinated in cold blood”.

Al Jazeera Media Network continues to demand a rapid, independent and transparent investigation into the killing of Abu Akleh, who was known as the Voice of the Palestinians.

On the day of her funeral, Israeli forces stormed the procession and started beating mourners, causing pallbearers to almost drop her casket, drawing global condemnation.

The letter demanded “detailed updates on the progress of this effort” within 30 days. The call comes as Biden reportedly plans a visit to Israel and Saudi Arabia in the coming month.

The senators’ calls underscore the pressure from US lawmakers on the issue. Last month, dozens of US legislators signed a letter demanding the FBI investigate the killing of Abu Akleh.

Israel’s military prosecutor initially called on the army to conduct an in-depth investigation, before Israeli media reported that the military had no plans to launch a criminal investigation.

Meanwhile, the US state department has continued calls for a “thorough and transparent” investigation into the killing, but stopped short of calling for an independent probe.

The Palestinian Authority (PA) announced last month the results of an investigation into the killing of Abu Akleh, saying that it shows Israeli forces deliberately shot and killed the veteran reporter. The findings echoed the results of a preliminary investigation announced weeks ago.

The PA, which also filed a complaint with the International Criminal Court (ICC) over the killing, argues that Israel authorities cannot be trusted to conduct an impartial investigation as they remain suspects in the killing.