George Zimmerman, who shot dead unarmed teenager Trayvon Martin sparking a nationwide debate in the US about race and self-defence, has been accused of pointing a shotgun at his girlfriend, police said last night.

Zimmerman, who was acquitted of second-degree murder and manslaughter in a trial earlier this year, was detained after police were called to the house he shared with his girlfriend in Apopka, northwest of Orlando.

He was charged with aggravated assault, battery and criminal mischief after an apparent argument with Samantha Scheibe, Chief Sheriff's Deputy Dennis Lemma said. No one was hurt in the alleged incident and no one else was at the home at the time of the arrest.

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Deputies said Zimmerman had barricaded himself inside by wedging furniture against the door before officers arrived. Ms Scheibe was outside the home and gave deputies a key to get inside. Once deputies entered the house Zimmerman did not resist and was not armed.

Neighbour Catherine Cantrell said she believed Zimmerman had been living there for at least a month. "I'm in absolute shock. He was never outside. It's not like he was out flaunting around," she said. Zimmerman and his estranged wife were involved in a domestic dispute in September. Police said no charges were filed against either of them because of a lack of evidence but it is thought to have occurred just days after Shellie Zimmerman filed divorce papers.