Hacker group Anonymous on Friday vandalized the website of a major US prison contractor in the latest salvo in an anti-police campaign.

Anonymous subgroup "Antisec" took credit for replacing The Geo Group website home page with a rap song dedicated in part to convicted murderer Mumia Abu-Jamal and a message condemning prisons and policing in the United States.

Mumia Abu-Jamal, whose birth name is Wesley Cook, is a former Black Panther and radio journalist serving a life sentence for the 1981 shooting death of a police officer in Philadelphia.

Activists around the world have rallied in support of the former Death Row inmate, who they contend fell prey to racism in the justice system.

"As part of our ongoing efforts to dismantle the prison industrial complex, we attacked one of the largest private prison corporations in the US - Geo Group," Anonymous said in a message posted at the Geo Group website.

"We are acting in solidarity with all those who have ever been wrongfully profiled, arrested, brutalized, incarcerated, and have had all dignity and humanity stripped from them as they are cast into the gulags of America."

The Geo Group manages prisons, mental health facilities, or detention centers in Australia, Britain, South Africa, and North America. The corporation reported $77.5 million in net profit on $1.6 billion in revenue last year.

Anonymous took credit Thursday for an online raid of the Los Angeles Police Canine Association and the posting of personal and potentially embarrassing information.

"Over the past three weeks, we in the cabin have been targeting law enforcement sites across the United States," hackers said in a message atop a file at Pastebin.com containing officers' addresses, phone numbers and more.

"Be it for injustices they have allowed through ignorance or naivety, taken part in, or to point out the fact that their insecurity failed to protect the safety of those they took an oath to serve," the group said of its motives.

The hackers claimed to have gotten the addresses of more than 1,000 officers along with information from police warrants and court summonses as well as about informants in their weeks-long series of attacks on police computers.

Anonymous law enforcement targets in recent weeks have included the websites of the Central Intelligence Agency and the Federal Bureau of Investigation.