Has MacIntyre been exposed?

He has been shot at, mugged at knifepoint and faced a £50,000 contract on his life. But can Donal MacIntyre survive the beating television critics have given him in recent days? His new series, MacIntyre Investigates, has been variously called "an absolute fiasco" (Daily Mirror), "ludicrous" (The Times) and "lame" (Daily Mail). To The Independent's Thomas Sutcliffe, the 36-year-old Dubliner has "all the journalistic impulses of a soft-shelled crab"; to the Daily Mirror's Jim Shelley, he is simply "the worst undercover reporter in England". That's not bad going after two programmes.

Meanwhile, BBC1's viewers have delivered their own critical verdict on his undercover exploits. Ratings are well down on the 7 million his first series achieved: 4.1 million watched him lose his laptop to a Brixton mugger 13 days ago, whereas 6.9 million chose to watch Bad Girls on ITV1. Last Thursday's programme on the powerful drug methamphetamine attracted just 3.7 million viewers - 18 per cent of the audience. The question now being asked within the BBC is why MacIntyre is drawing barely more viewers than Panorama, while costing at least four times its programme budget.

MacIntyre has described his undercover work - most successfully in exposing football hooligans and abuse in care homes - as "exhilarating, dangerous and stressful". But resentment is growing within the corporation that his high-profile exposés are squeezing out serious investigations in favour of visually appealing stunts. A senior BBC current affairs figure dismisses Mac-Intyre's investigation into street crime in south London as "utterly predictable and trivial". "It's dreadful self-aggrandisement and a terrible waste of licence-payers' money. Some serious auditing is needed. There are people in other parts of the BBC with better honed skills, and you could get a much bigger bang for your buck."

The BBC will not disclose the cost of the three programmes scheduled, plus any others that may follow, but a figure of more than £2 million has been mentioned in internal meetings. (A spokeswoman says the true figure is "nothing near £2 million" but will not elaborate.) An episode of Panorama, by contrast, typically costs £100,000-£150,000. In return, Lorraine Heggessey, BBC1's controller, expects MacIntyre Investigates to deliver the ratings - a pressure that other investigative journalists believe undermines its editorial integrity.

Such "commercially driven decision-making" has placed MacIntyre in an untenable position, according to Nick Davies, the investigative writer and broadcaster. "Donal is a charming and good-looking man who's willing to put himself in situations that are exciting and sexy. That kind of programme should drive up ratings. The big worry is that it's really entertainment, not investigation - and because it sucks funds away from the more important factual programming, there's a real knock-on problem."

Davies, who trains other investigative journalists, worries that programmes such as MacIntyre's face pressure to deliver "good TV" - even if that compromises the story. "There's a reversal of journalistic logic in television investigations - Donal's team was scrambling around looking for something to infiltrate, rather than starting with the issue." Davies himself was twice approached by a production company working for Channel 4, which sought help in getting an undercover reporter into a brothel and then a strip club. "Guess what they have in common," he reflects. "There's no shortage of real stories that need investigating - but what Channel 4 wants is breasts."

For all the criticisms, MacIntyre's methods have faced in recent days - and tomorrow's programme, in which a prostitute walks out on his film crew, may bring more - he has solid journalistic credentials. Originally a writer for Ireland's Sunday Tribune and the Irish Press, he moved to television in 1993 and began working undercover for the BBC sports series On The Line. He won awards for exposing cruelty in Irish greyhound racing, and then spent a year undercover as a bouncer for World in Action. This won him two Royal Television Society awards. His first BBC series, MacIntyre Undercover, made his name but with mixed journalistic results: the BBC settled out of court after the Elite model agency sued. MacIntyre, meanwhile, is suing Kent Police over remarks about the accuracy of his care-home investigation.

In this second series, it is his softer targets that have brought criticisms. Paul Foot dismisses his approach as "the Roger Cook form of investigation - it's just about getting a good piece of television". Foot believes MacIntyre was misguided to take on Brixton's street criminals, an easy target.

"Fundamental to the idea of an investigative journalist is the notion that you go for the strong rather than the weak. If what you're really doing is grubbing down among the weak to find what no one would deny is wrong, you're just shoring up the existing operation. It's our job to challenge the existing order," says Foot.

As for MacIntyre, he dismisses his critics as "lazy, bitchy" journalists. "People who dismiss (the programme) as 'entertainment' fail to see the documentary point or the journalism behind it," he says. "Where else have you heard that stolen mobile phones end up in Africa? We addressed the connection between drugs and street theft, and the Del Boy culture that allows people to dissociate themselves from the crimes that lead to goods ending up on the street."

But Heggessey, who has commissioned him to front a £3 million series on extreme weather this autumn, may now be questioning whether MacIntyre can live up to his billing. His investigative peers, meanwhile, have already made up their minds.