A Colombian journalist was shot in the head by a helmet-clad assassin in front of the radio station where she worked.

Shocking footage of the murder captures a man creeping up behind Flor Alba Nunez Vargas as she goes to unlock the door, killing her with a single shot.

The cold-blooded killing took place in the southern city of Pitalito on Thursday.

Caught on camera: CCTV footage shows the shocking murder of Colombian journalist Flor Alba Nunez Vargas outside the radio station where she worked

CCTV shows Ms Vargas as she gets her keys from her bag, unaware the assassin is lurking just behind her.

The man then fires the shot before casually walking away from the scene to a nearby accomplice, waiting on a motorbike.

The 25-year-old reporter was known for being a tireless campaigner against drugs, people trafficking and corruption.

She had recently received threats over local election coverage and for publishing a picture of a criminal gang who had been blamed for a town hall break-in.

Pictures and an interview of several men who reportedly hanged a dog from a lamppost after it attacked them, had also caused uproar and led to threats.

Calculated: Flor Alba Nunez Vargas can be seen getting her keys from her bag as the helmet-clad assassin casually walks up behind her

Cold blooded: The killer casually walks up behind the 25-year-old journalist before killing her with a single bullet

The journalist had also reported on the arrests and trials of drug traffickers and other local criminals who could have been angered by her coverage, local reports claim.

Ms Vargas hosted a popular programme called La Preferida Stereo on a radio station called La Preferida FM - Spanish for Preferred FM.

Colleagues described her as a 'passionate journalist' and said in a statement: 'We profoundly regret the murder of our companion.'

'We hope this doesn't remain as just another unpunished crime. Peace in death.'

The Colombian government has announced a reward for information leading to the arrest of the killers.

Huila Police chief Santiago Camelo believes contract killers are responsible for the crime and appealed for the local community for information.

He said: 'We are on the trail of the murderer who appears to have escaped by motorbike.

'We cannot at this stage specify the cause of this terrible event.'