The boss of pubs chain JD Wetherspoon today warned the drunken antics of sports stars and celebrities were fuelling wider problems over alcohol abuse - as well as having a detrimental effect on sales.

Chairman Tim Martin voiced his concerns as the impact of last year's smoking ban and cost pressures led to a 13% fall in pre-tax profits to £28.5 million in the six months to January 27.

Chairman Tim Martin said there was "rightly considerable concern" over yobbish behaviour from a minority - but added that police were wrong to focus on underage drinking when the main problem was cultural.

He said: "This is demonstrated by examples of poor behaviour by a number of celebrities during the recent televised Brit Awards and by habitual drunken celebrations in the context of sporting events and other occasions, which then receive huge press coverage.

"This sort of behaviour is not a new phenomenon, and is frequently replicated by the general public during birthday parties, stag and hen parties and so on."

Mr Martin added that poor behaviour was also bad news for the pubs trade as it was intimidating for most other customers. He added: "The correct approach for the authorities, in our opinion, is to concentrate on the message that pubs and drinking are legitimate activities, but they bring an obligation to behave responsibly."

Mr Martin highlighted the raucous celebrations of the Ashes-winning England cricket team in 2005, whose two-day victory binge was splashed across the press. He added: "There is quite a lot of media criticism of pubs and reference to 24-hour drinking, which doesn't really exist.  But the press has to bear some responsibility for printing pictures of people falling out of clubs at four in the morning."

The Wetherspoon boss believes that police resources targeted at keeping underage people out of pubs did not address the issue as their parents "actively collaborate" in their drinking.  He added: "The current effort to prevent under 18 year olds drinking is likely to fail, since it is difficult to enforce, especially since almost all parents permit these age groups to drink."

Wetherspoon, which has 681 pubs and 20,000 staff, said recent trading had continued the trend of strong growth in food sales, but falling drinks sales, following the smoking ban introduced in England last July.

Overall like-for-like sales across the group fell 2% and while Wetherspoon expects a recovery in bar sales as customers adjust to the new regime, it admitted that the "exact timing of this is still uncertain".

The company is positioning itself for the long-term impact of non-smoking pubs through its increased food offering and move into breakfast meals.

Wetherspoon now sells around 514,000 coffees and teas a week, 12% higher than last year. But the group is not immune from the effect of rising energy prices as well as soaring food and beer costs, adding that the cost pressures left it with a "slightly more cautious" outlook for the rest of the financial year.