Parents of missing British girl Madeleine McCann have received an onslaught of online abuse and death threats in recent weeks, officials said Thursday.

London Metropolis Police confirmed to NBC News that the McCanns have been receiving graphic social media messages on Facebook and Twitter calling for violence against the couple.

Three-year-old Madeleine disappeared from her hotel room in 2007 during a trip to Portugal while her parents dined nearby with other friends. Mother Kate and her husband, Gerry were originally suspects according to the Portuguese police, but were cleared in July 2008.

The McCanns sued several British newspapers over their coverage of the case. Publications such as the Daily Star, Sunday Express and Daily Express ran front-page apologies for writing that the parents were to blame for the little girl's death and paid the couple nearly $900,000 in damages.

An 80-page document detailing the violent threats was submitted to the police on Sept. 9. The compilation of numerous threats and abusive words were collected by members of the public who came to the defense of Kate and Gerry.

Many of the messages suggested the McCanns should be tortured and killed, one saying they should "burn in hell."

"I hope that the McCanns are living in total misery," another message said.

Yet another wrote in an online forum," "I want to see them smashed up the back of a bus or trampled by horses."

Britain's Sky News was the first to report the content of these messages. Police said they were working with the McCanns and the U.K.'s Crown Prosecution Service "to find the best way to take this forward."

"In consultation with the Crown Prosecution Service and the McCann family the material will now be assessed and decisions made as to what further action, if any, should be taken," the Metropolitan Police told the people who submitted the document.