WikiLeaks has offered a reward of $50,000 for any footage or cockpit audio from the US warplane that bombed a Doctors Without Borders hospital in the Afghan city of Kunduz.

“We are raising a $50,000 bounty to obtain the footage, the cockpit audio, the inquiry report and other relevant materials such as the Rules of Engagement active at the time,” Wikileaks wrote on its website.

On October 3, a Doctors Without Borders hospital in Kunduz was repeatedly bombed by a US AC-130 gunship, leading to the deaths of 22 patients and staff.

“The AC-130 records its attacks with high resolution gun cameras,” Wikileaks said in its statement. “According to military procedure, this footage should have been retained along with the cockpit audio. A post-massacre inquiry report referred to as an ‘AR 15-6’ should have also been commissioned.”

Washington has admitted responsibility for the bombing, saying that the hospital was hit “mistakenly.”

On Wednesday, President Barack Obama called Doctors Without Borders International’s president, Dr. Joanne Liu, on the phone “to apologize and express his condolences for the MSF staff and patients.”

Doctors Without Borders have urged an independent investigation into the deadly US airstrike to determine whether the attack should be regarded as a war crime.

READ MORE: ‘Patients were burning in their beds’: Witnesses recall horrific Kunduz hospital airstrike

Such an investigation should gather evidence from the US, NATO and Afghanistan, as well as testimonies of the Kunduz hospital staff and patients, they said.

Depending on the findings, Doctors Without Borders would consider whether to file charges against Washington for loss of life and partial destruction of the hospital in Kunduz.

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