Gunman was mentally unstable, not radical

The ex-wife of the Orlando massacre gunman says he was violent and mentally unstable during their relationship but never expressed Islamist militant leanings.

Sitora Yusufiy spoke briefly to reporters late on Sunday outside her Colorado home insisting that Sunday's massacre was not caused by political or religious fanaticism but rather mental illness.

"Emotional instability, sickness, he was mentally unstable, ill," she said.

Yusufiy was woken on Sunday morning by a call from her parents to alert her to the shooting spree at a gay nightclub in Florida.

Police say Omar Mateen killed 50 people before he was killed when officers stormed the building.

Yusufiy said she was grieving for the victims and their families.

She said she met Mateen through an online dating service.

"In the beginning he was a normal being, who loved to joke, loved to have fun."

Within a few months of their 2009 marriage he became violently abusive toward her.

Yusufiy described him as bipolar and suggested that a "history with steroids" might have been a cause of his rages.

He kept her "hostage" and isolated, before her family came to Florida and "literally rescued me ... out of his arms".

They were together four months and have had "no contact" since, Yusufiy said.

"He did follow religion. He did practice, and he had his faith," she said.

But she saw "no sign" of religious radicalism in the New York-born Afghan-American.

The FBI said that Mateen called police during the three-hour nightclub standoff, talking to emergency operators about Islamic State.