A veteran Greek crime reporter was gunned down outside his Athens home on Friday, officials said, shocking the country where media killings are rare.

Giorgos Karaivaz, who worked for private TV station Star and also ran the news blog bloko.gr, was shot several times as he exited his car outside his house in the southern Athens district of Alimos, witnesses said.

"The murder has shocked us all," government spokeswoman Aristotelia Peloni said in a statement, adding that authorities were investigating the killing.

A police source said the journalist, who was in his fifties, had been shot by two men on a motorbike. Seventeen bullet casings were recovered from the scene.

Witnesses offered chilling accounts of the scene after his death.

"I tried to park my car where he lay. I thought someone had fainted. He was lying face down... blood was flowing onto the sidewalk," a woman who lives in the neighbourhood told reporters.

Greek government spokeswoman Aristotelia Peloni said the authorities were investigating the killing
Greek government spokeswoman Aristotelia Peloni said the authorities were investigating the killing Eurokinissi / Yiannis PANAGOPOULOS

Flowers were left Friday on the spot where the slain journalist fell.

The European Union slammed the killing as "a despicable, cowardly act".

"Europe stands for freedom. And freedom of press may be the most sacred of all. Journalists must be able to work safely. My thoughts are with the family of George Karaivaz. I hope the criminals are soon brought to justice," EU Commissioner Ursula von der Leyen tweeted Friday.

While Greek media offices are frequently targeted in firebomb and vandalism attacks, journalist killings are rare in the country.

Some journalists request police protection after receiving threats, but Karaivaz was unguarded.

A police source said the journalist had been shot by two men on a motorbike
A police source said the journalist had been shot by two men on a motorbike Eurokinissi / Yiannis PANAGOPOULOS

One of Greece's longest-tenured and best known crime reporters, Karaivaz was married with a 21-year-old son.

A statement on Karaivaz's blog confirmed his death, and said he was targeted because of his work.

"Somebody chose to silence him, to stop him with bullets from writing his stories," it said.

A police officer who knew the journalist praised his work, saying "he was extremely intelligent and one of the few fighting reporters in the field".

"It was not his style to request protection," the police officer told AFP, speaking on condition of anonymity.

The shooting occurred at a time when Greek authorities had received criticism for allocating too many police guards to a controversial TV presenter.

Hours before Karaivaz' murder, Citizen's Protection Minister Michalis Chrysohoidis had suggested in parliament that the state protection system was being exploited by '(rodents) of the public sphere' who did not deserve it.

"For the last 20 years, every (police) minister has tried to take back (officers) from 'VIP duty' and put them back on the front line," the minister said.

In July, tabloid newspaper owner Stefanos Chios survived after being shot in the neck and chest by a hooded man outside his home.

The case is still under investigation.

In 2010, radio manager, blogger and investigative journalist Socratis Giolias was gunned down outside his home.

At the time, state TV NET said he had been working on a story about corruption.

A shadowy far-left group claimed responsibility for the crime but the case was never solved.