Macintyre said his work was becoming increasingly dangerous and he wanted to return to everyday life.

The BBC's Adam Mynott: "At extreme personal risk he followed the thugs abroad"

His decision came on the day the acclaimed Radio 5 Live journalist began his new series of reports for BBC1 examining football hooliganism, private care workers and fashion photography.

Speaking to BBC News Online, he said: "I realise this is a finishing line for me.

"'Macintyre Uncovered' is a one-off series and it's the last time I go undercover. It won't be safe or viable from now on.

"It's clearly an abnormal lifestyle and the more you live it, the more you are removed from the normal life you once used to lead.

"Once the abnormal becomes the normal, you have changed - and I don't want that."

'No plans'

He said he had no plans for the future and was simply looking forward to spending Christmas with his family.

Last year, he spent Christmas in a care home while working on an undercover expose.

Macintyre sharpened his investigative teeth while working on ITV's World in Action programme.

An investigation exposing the drug trade won him two Royal Television Society awards - but with it came two death threats.

The violence continued as he uncovered criminal activity in his reports for the BBC.

In the opening TV programme, MacIntyre infiltrates a group of soccer fans and their world of organised violence, racism and far right politics.

During filming, he was attacked by a gang of hooligans in Copenhagen.

Safe house

Following his earlier Radio 5 Live investigations, he was forced to sell his home and go into hiding.

The BBC has since supplied him with a safe house and full security protection.

He said: "People attach phrases like 'courageous' and 'brave' to the work I do.

"But you must remember police officers and squaddies do this work all the time. It's not just me."

While Macintyre relies on his gift of the gab and his ability to "disappear into the wallpaper" as he calls it, he also requires the latest technology to record his subjects covertly.

Cameras sewn into clothes

A member of the production team - nicknamed "Q" after the James Bond character - adapted off-the-street High Street equipment like MiniDisc and MiniDV recorders for the series.

Donal Macintyre: "I've had death threats"

Macintyre found himself out on the road with cameras sewn into his clothes and equipment strapped to his body.

The kit had to be strong enough to sustain attacks on him and and protect the recorded footage.

Some might question these covert techniques, but Macintyre said strict procedures and guidelines were in place.

"Journalistically, technology can be blunt. It is a tool of last resort.

"We only use it in narrow circumstances and these considerations are dictated to by your journalistic ethics, by the BBC and by compliance committees."