The Florida man accused of second-degree murder for shooting unarmed black teenager Trayvon Martin was granted bail Friday but won't go free until his security can be assured.

A judge in Sanford, Fla., decided that George Zimmerman can be released on a $150,000 US bond, far less than the $1 million prosecutors were requesting. Zimmerman and his family will have to post $15,000 of that in cash and the rest as collateral.

Circuit Judge Kenneth Lester set several other bail conditions on Zimmerman:

• He must wear an electronic monitoring device and surrender his passport.
• He can't possess any firearms.
• He can't use alcohol or drugs.
• He must observe a 7 p.m. to 6 a.m. curfew and report to authorities every three days.

In an unexpected move, 28-year-old Zimmerman, dressed in a dark grey suit with his hands shackled, took the stand at Friday's hearing to apologize to Martin's parents, who were in the courtroom.

"I wanted to say I am sorry for the loss of your son. I did not know how old he was — I thought he was a little bit younger than I am. And I did not know if he was armed or not," Zimmerman said.

The prosecution asked Zimmerman why it took him so long to apologize. He replied that he had been told not to communicate with the family, but had said he felt sorry for them in one of his statements to police.

Lawyers for Martin's parents said the apology was disappointing.

"This was the most disingenuous and unfair thing I've seen," said Natalie Jackson, one of the lawyers for Tracy Martin and Sybrina Fulton. "This was the most unmeaningful apology."

Prosecution alleges racial profiling

Zimmerman, a neighbourhood watch volunteer at a gated community in Sanford, is charged with murdering 17-year-old Martin on Feb. 26. That evening, Zimmerman saw Martin walking through the community — the teen was staying there at his father's fiancée's house — and then called police and followed him. In a confrontation that ensued, Zimmerman shot Martin, though he claims that it was in self-defence and that Martin was the aggressor.

Early in Friday's hearing, an investigator on the case outlined the prosecution's central allegation, saying that Zimmerman shot Martin in a clear instance of racial profiling.

"Zimmerman saw Martin and formed an idea in his head and contacted the Sanford Police Department with no facts," Dale Gilbreath testified.

From left, Trayvon Martin's parents Tracy Martin and Sybrina Fulton, their attorney Benjamin Crump and attorney Natalie Jackson leave court after George Zimmerman's bail hearing on Friday. Marin and Fulton did not comment to the media. (Roberto Gonzalez/AFP/Getty)

The case has sparked widespread protests and denunciations across the United States because Zimmerman was not charged until 44 days later. Authorities said they didn't have enough evidence to overcome Florida's so-called stand your ground law, which allows the use of lethal force in self-defence, but detractors said it was because Martin is black. Zimmerman himself has a white father and Peruvian-born mother and identifies as Hispanic.

Zimmerman's wife and parents also testified at Friday's hearing, but by phone, out of fear for their safety.

Shellie Nicole Zimmerman said she doesn't think her husband is a danger to the community, and that she had "no concerns whatsoever" about his getting bail. She did say, however, that she was worried for her husband's and her own security.

"You had evidence of a concern both for your safety and that of your husband. Is that correct?" defence lawyer Mark O'Mara asked.

"That's correct," she replied.

The prosecutor also asked her about two incidents they said showed George Zimmerman has a violent nature. In one, Zimmerman took anger management courses after an undercover police officer said Zimmerman attacked him. A former girlfriend also once accused Zimmerman of assaulting her.

Zimmerman's wife replied that she doesn't think her husband has anger problems.

His father, Robert Zimmerman Sr., also spoke to the court by telephone, as did his mother, Gladys Zimmerman.

Zimmerman is not expected to be released immediately, the judge said, as there are still some conditions to be worked out, including whether he will be allowed to leave Florida because of the concerns over his safety. It could be a few days before he is freed.

With files from The Associated Press