US gunman Omar Mateen identified himself as an Islamic soldier in calls with authorities during his rampage and demanded to a crisis negotiator that the country's army "stop bombing Syria and Iraq", according to transcripts released by the FBI.
The partial transcripts were of a 911 call made by Mateen and three conversations he had with the police crisis negotiators during the worst mass shooting in modern US history, in which 49 people died and dozens were wounded.
Those communications, along with Facebook posts and searches Mateen made around the time of the shootings, add to the public understanding of the final hours of Mateen's life and to the possible motivations behind the rampage.
The first call came more than a half-hour after shots rang out, when Mateen told a 911 operator, "Praise be to God, and prayers as well as peace be upon the prophet of God," he told the dispatcher, referring to God in Arabic.
"I let you know, I'm in Orlando and I did the shootings."
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During the 50-second call with a dispatcher, Mateen "made murderous statements in a chilling, calm and deliberate manner," Ronald Hopper, FBI assistant special agent in charge in Orlando, said during a news conference.
However, there is no evidence Mateen was directed by a foreign terrorist group, and he was radicalised domestically and on his own, Hopper said.
Mateen's name and the groups and people to whom he pledged allegiance were initially omitted from the excerpt.
But the Justice Department reversed course later on Monday, providing a more complete transcript confirming Mateen pledged allegiance to Abu Bakr al-Baghdadi, the leader of the Islamic State.
The extremist group encourages its followers who seek to commit violence in its name to make public pledges of support.
The Justice Department said in a statement it initially withheld the names so as not to give extremists "a publicity platform for hateful propaganda," but the omissions became an unnecessary distraction.
Shortly after the call with a 911 operator, Mateen had three conversations with crisis negotiators in which he identified himself as an Islamic soldier and told a negotiator to tell the US to stop bombing Syria and Iraq.
He said that was why he was "out here right now," according to the excerpt.
Hopper also said on Monday that the tapes would not be released out of respect for the victims.
Also at Monday's news conference, Orlando police Chief John Mina said that if any fire from responding officers hit victims at the club, gunman Mateen bears the responsibility.
He wouldn't give further details but said: "Here's what I will tell you. Those killings are on the suspect, on the suspect alone in my mind". He stressed that the officers "acted heroically".
He said an exchange of fire between police and Mateen shortly after 2am prompted the attacker to retreat into a bathroom and take hostages, shifting the incident from a shooting to a hostage-taking.
Mina said there was no additional gunfire for about three hours until the SWAT team entered the building, although survivors have described at least some firing taking place inside one of the bathrooms.
Meanwhile, hospital officials said four people remained in critical condition Monday morning, more than a week after they were wounded in the attack.
