It took a British diplomat on Thursday morning to open the doors of a rarefied room in a star hotel to foul air from city streets.

A "greener roadmap for global business" was being drawn up when British deputy high commissioner Simon Wilson pointed to the poison fumes being belched out by government and private vehicles.

The foreign guest of honour went beyond his prepared speech at Environment Partnership Summit 2008 and blamed the Buddhadeb Bhattacharjee government for not tackling the crisis.

"The limit for respirable particulate matter is 60 micrograms per cubic metre of air but in Calcutta, the average figure is about 100.... As I come from Delhi and other places to Calcutta, I can easily feel the difference," said Wilson.

The diplomat rapped the government for failing to convert "fume-belching" vehicles on roads to alternative fuels, like CNG or LPG.

"It is being done even in smaller cities, but not much action is seen in Calcutta," rued Wilson. "The government can lead the way by converting the state-owned buses to alternative fuel," he added.

Choking on Wilson's words were officials from the state environment department, the state pollution control and Indian Chamber of Commerce.

"The issue (auto emission in Calcutta) must be addressed immediately. I request the government of West Bengal to get a grip on environmental pollution and speed up the conversion to greener fuels" urged Wilson.

The British clean-air attack on Team Buddha comes 10 days after Gordon Brown had declared major parts of London 'low emission zones', with diesel lorries forced to follow strict emission norms or face a fine of up to £1,000 a day.

Calcutta remains a high emission zone mainly due to the government's failure to slam the brakes on polluting vehicles and the attendance roster at Thursday's high-profile summit reflected how serious the government is about clean air.

Chief minister Buddhadeb Bhattacharjee, a self-professed green enthusiast, was missing in action, having earlier stated his inability to attend the summit. Environment minister Sailen Sarkar was taken ill at the last moment, while the chairman of the state pollution control board, Ashok Nath Bose, was "very busy" and so could not attend the meeting, organised jointly by his own team.

"It's a fact that air pollution is a real concern in Calcutta," admitted environment secretary M.L. Meena, the seniormost green official at the summit. "We have been trying to replace old vehicles and convert autorickshaws to LPG. We had even released a grant to the transport department to subsidise the conversion...."

The same tone of bureaucratic helplessness was heard from transport secretary Sumantra Chowdhury later in the day. "We have to work within a government framework. What else can I say?"

Transport minister Subhas Chakraborty could not be contacted.

But his namesake, Subhash Dutta, did not lose the chance to highlight the city's plight. "After environmentalists, the high court, central agencies and the governor, it is now the turn of foreign guests to blame the government for air pollution," he said.