WASHINGTON (AFP) – US Navy SEALs who led a raid on Osama bin Laden's compound found an AK-47 and a pistol in his room, a US official told AFP, offering more details about the operation.

"He had weapons in his room, more than one," said the official, who spoke on condition of anonymity.

"He was not compliant. He did not surrender," the official said.

Divulging more details of the raid after conflicting accounts from the White House, the official said the US commandos encountered only one man who was armed at the compound -- bin Laden's courier -- who fired the only shots near the start of the nearly 40-minute operation.

The courier "was the only one who opened fire," he said.

US media reported that the courier was killed along with his wife in a guesthouse adjacent to the main residence where Bin Laden was hiding.

At the larger three-storey building, the Americans shot and killed the courier's brother, who reportedly had one hand behind his back.

Making their way up the stairs, they saw Bin Laden's son, who "lunged" towards them, the New York Times reported.

On the third floor, Bin Laden was shot in the chest and head.

The official insisted the US team faced an array of potential dangers by venturing into the hideout of Al-Qaeda's mastermind, and were prepared for the possibility he and his comrades might be wearing suicide vests or have explosives planted ready to be triggered.

"It's important to see the context," he said.

"If you are going to a house where the people have been hostile, it's Osama bin Laden's house, and you see him in a room and he's not compliant -- what would you do?"

Given the possible threats, the gunfire from the courier and Bin Laden's reputation, "the team made the right decision."

The administration's account of the raid has shifted, as initially the White House, intelligence and defense officials had portrayed the nearly 40-minute raid as a raging gun battle, with Bin Laden resisting and allegedly using a woman as a shield.

White House spokesman Jay Carney on Tuesday said the US troops "were engaged in a firefight throughout the operation."

The US official confirmed the SEAL unit found a false door at one point and obstacles in the stairway of Bin Laden's residence. They also discovered a number of other weapons apart from the assault rifle and the Russian pistol in the Al-Qaeda leader's bedroom, he said.

To detect possible explosives or to sniff out suspects hiding, the Navy unit brought along a specially trained dog in the raid, media reported.

Bin Laden, the world's most wanted man since the attacks of September 11, 2001, appeared to have prepared for a quick escape, the official said.

"He had money sown into his clothing and also phone numbers sown into his clothing."