An international panel is ready to investigate the deadly US bombing of a Médecins sans Frontières (MSF) field hospital in Afghanistan, the group said on Wednesday.

But before the investigation into potential US war crimes can begin, the International Humanitarian Fact Finding Committee (IHFFC) requires assurances from Barack Obama and the Afghan president, Ashraf Ghani, that their governments will comply.

The prospect of a war crimes inquiry raises the political stakes for Obama significantly: assenting to the investigation would be likely to trigger domestic political backlash, while obstructing it would leave the US open to accusations that it is covering up an incident which MSF has called an attack on the law of war itself.

The White House was noncommittal on Wednesday but signaled it was unpersuaded by MSF’s claims that an independent inquiry is necessary.

“We have received apologies and condolences, but this is not enough,” Joanne Liu, the international president of MSF, said in a Wednesday statement.

“We are still in the dark about why a well-known hospital full of patients and medical staff was repeatedly bombarded for more than an hour. We need to understand what happened and why.”

The IHFFC, established in 1990 but never before activated, said that “on its own initiative” it offered its investigative services to the US and Afghan governments through letters sent on 7 October.

“It is for the concerned Governments to decide whether they wish to rely on the IHFFC. The IHFFC can only act based on the consent of the concerned State or States. The IHFFC cannot give any further information at this stage,” the organization said in a Wednesday press announcement.

The 3 October airstrike, from a US AC-130 gunship and called in by a US special operations team in response to an Afghan request for air support, left 22 doctors, nurses and patients dead and 37 wounded.

MSF has consistently said that it provided the GPS coordinates of the hospital, established in 2011, to the US and Afghan governments, aggressively challenging the US suggestion that it did not know the target of the airstrike was a hospital. The strike appears to have violated the Pentagon’s own instructions on compliance with international law, which holds battlefield hospitals in a privileged position, off limits to combat. The US military has repeatedly shifted its account of the airstrike.

Obama apologized to MSF last week but provided no commitment that he would cooperate with the IHFCC inquiry that MSF has demanded. Although the US, Nato and Afghanistan are investigating the strike, MSF has rejected their inquiries as insufficient, since all are parties to the Afghanistan war.

At the White House, spokesman Josh Earnest signaled that the administration would oppose an IHFCC investigation.

“The administration has confidence that the investigation that is currently under way by the Department of Defense will provide the full accounting of the situation that the president has asked for,” Earnest said.