LONDON — Journalists at a tabloid hacked the voicemail of a high-profile missing teenage girl, giving false hope to her family that she was alive when she had in fact been murdered, a report said Monday.

In a grim new twist to the long-running phone-hacking row at the Rupert Murdoch-owned News of the World weekly, The Guardian said police were investigating claims that Milly Dowler, who disappeared in 2002 aged 13, was among those targeted.

Journalists at the News of The World hired investigators to hack into Dowler's phone and listen to increasingly desperate messages left by her parents and friends as the days went past without any word from the teenager, the report said.

When her voicemail box became full, they deleted a few of the messages to make room for new ones -- an action that her loved ones mistakenly took as proof that Dowler was still alive and using her phone, it said.

It also caused confusion among the police detectives investigating her disappearance, and potentially destroyed valuable evidence, the report said.

Her parents, Sally and Bob Dowler, said they would be pursuing a claim for damages against the tabloid following the revelations, which came just days after her murderer was locked up for life.

"It is distress heaped upon tragedy to learn that the News of the World had no humanity at such a terrible time," said their lawyer Mark Lewis.

"The fact that they were prepared to act in such a heinous way that could have jeopardised the police investigation and given them false hope is despicable."

The tabloid's owners, News International, declined to comment.

Levi Bellfield was convicted on June 23 of abducting and murdering Milly in Walton-on-Thames, near London. Her bones were found six months later in a forest.

Monday's report is the latest twist to the long-running phone-hacking scandal at the News of The World, Britain's top-selling Sunday title, which has a reputation for showbusiness scoops and sex scandals.

A journalist and a private investigator were jailed in 2007, but the police investigation was reopened this year and since then five journalists, including three who work at the tabloid, have been arrested.

The newspaper has also admitted liability in several civil cases, including that of actress Sienna Miller, who received £100,000 in damages.