ORLANDO, Fla. -- The U.S. neighbourhood watch volunteer who killed an unarmed black teenager can be released from jail on $1 million bond while he awaits trial in a case that provoked nationwide protests, a judge ruled Thursday.

Circuit Judge Kenneth Lester granted bond to George Zimmerman for a second time. The judge had revoked Zimmerman's $150,000 bond last month after prosecutors said Zimmerman and his wife misled the court about how much money they had.

"It is entirely reasonable for this court to find that, but for the requirement that he be placed on electronic monitoring, the defendant and his wife would have fled the United States with at least $130,000 of other people's money," Lester wrote.

Zimmerman has been charged with second-degree murder for fatally shooting 17-year-old Trayvon Martin on Feb. 26 in a Florida gated community. Zimmerman has pleaded not guilty and claims the shooting was self-defence under the state's "stand your ground" law.

Martin's parents and supporters claim that the teenager was targeted because he was black and that Zimmerman started the confrontation. Zimmerman's father is white and his mother is Hispanic.

The 44 days between the shooting and Zimmerman's arrest inspired nationwide protests and prompted a U.S. Justice Department probe.

Prosecutors said a website Zimmerman created for his legal defence had raised $135,000 at the time of his first bond hearing in April. Zimmerman and his wife did not mention the money then, and Shellie Zimmerman said the couple had limited resources because she was a student and he wasn't working.

The judge expressed his unhappiness with Zimmerman and said his actions suggest a possibility that he was preparing to flee to avoid prosecution.

"Under any definition, the defendant has flaunted the system," Lester wrote in the order.

Lester said he was granting bond because Zimmerman posed no threat to the community, and Florida law requires that most defendants receive bond if they pose no threat and can assure their presence for trial. The judge's order requires Zimmerman to be electronically monitored, prohibits him from opening a bank account or obtaining a passport and implements a 6 p.m. to 6 a.m. curfew. Zimmerman had been allowed to leave Florida under the conditions of his first bond release.

Zimmerman will have to pay a bail bond company $100,000 and have collateral worth $1 million. Neither Zimmerman nor his family has that amount in collateral, Zimmerman's attorney Mark O'Mara said on his website in an appeal to supporters to donate. The fund now has $211,000 in it, O'Mara said.

"For those who have given in the past, for those who have thought about giving ... now is the time to show your support," O'Mara said.

The defence lawyer has questioned why his client is in jail at all, arguing that Martin's actions led to his death.

O'Mara ultimately decided against calling his client to the stand during last Friday's bond hearing. During the first bond hearing, Zimmerman apologized to Martin's family.

The defence attorney called Zimmerman's father to testify and played an emergency call to police from the night Martin was killed. The call includes a disputed cry for help and the fatal gunshot. Robert Zimmerman said he was sure that was his son's cry.

Shellie Zimmerman has been charged with perjury. She is out of jail on $1,000 bond, and her arraignment is set for July 31.