Business travel is under environmental scrutiny, and top executives are reassessing how or whether they will travel to do business.

John Sauven, executive director of environmental campaigners Greenpeace, says: "Companies like Sky and Marks and Spencer are beginning to deal with the low-hanging fruit of using low emission vehicles, video conferencing and using trains where possible. But in terms of where we need to get to in cutting CO 2 emissions in the next 100 months, far more radical measures need to be taken.

"These need to extend beyond the greening of company headquarters to looking at the whole supply chain and end consumer use, whether it is products or services.

"There is no point in having a shiny green head office and then having your suppliers in China making your widgets using the most energy inefficient production processes, powered by filthy, polluting coal-fired power stations. Nor is their any point in your staff at HSBC driving hybrid cars if you have an investment portfolio that includes oil extraction from tar sands projects in Alberta, Canada. Companies need to have a strategy for carbon reduction across the whole of their operations."

So are companies going green to protect their reputations rather than being genuinely concerned for the environment? If a recent UK survey is to be believed, FTSE 100 companies are more concerned with creating an eco-friendly corporate image. When Chatsworth Communications surveyed 1,200 opinion formers, just 1 per cent said they believed environmental policies were the result of genuine concern. Respondents said the main motivation for UK companies to adopt green policies was to protect their reputation (27 per cent), followed by consumer pressure (20 per cent) and good business sense (18 per cent).

Marks and Spencer and HSBC were voted the top green winners - the companies making the most genuine green effort - while BP, Tesco and British Airways were considered to be most guilty of "greenwash" by respondents. But, for whatever reason, few big companies appear to be without environmental travel policies and some are surprisingly far-reaching.

Lloyds TSB, the UK high street bank, says it actively encourages employees to use alternatives to travelling, especially for internal meetings. Last year it increased audio-conferencing by 50 per cent, to almost 235,000 meetings. "This helped to reduce car and rail travel by 20m km," it says. Lloyds says its carbon footprint last year was equivalent to 189,373 tonnes of CO 2 and it has a target to reduce CO 2 emissions by 30 per cent by 2012 (based on 2002 levels).

The bank adds: "Our key objective is to reduce our footprint, not just to offset."

However, green travel is much more difficult for some companies to achieve than others. That is particularly true of big airlines and transport companies.

Take, for example, British Airways. BA says it was the first airline to introduce an offset scheme for passengers and is looking to develop its scheme in the coming months. The company says: "As part of this process, we are assessing how offsetting might relate to flights ground-based staff must take as part of their normal duties. As we are a global airline with operations in more than 60 countries, un-avoidable air travel may be more extensive for our staff than for employees in other industries."

For ground travel, staff are encouraged to use public transport wherever practical. Its 4,000 headquarters staff are encouraged to car share and, one day a week, are required to use an alternative to their own car to arrive at work.

Tristar, a leading chauffeur company, is another transport company that is addressing staff travel issues. Tristar provides services across the UK and, through a network of affiliates, in 38 countries. The company's fleet of 600 vehicles completes more than 400,000 journeys a year for its clients.

But Dean de Beer, its chief executive, says: "We actively encourage our office staff to use public transport to commute to and from work and many people do use the bus."

But the company's location, he says, is not particularly well served by public transport and many who might consider public transport are forced to use cars or motorbikes to get to and from work. This is exacerbated by the fact that it is a round-the-clock business. Mr de Beer adds: "With regard to our chauffeurs we put a lot of time and effort into allocating the first collection and last drop off of the day as close to their home as possible, thus minimising their commute and improving our operational efficiency."

Starwood Hotels & Resorts, a leading hotel and leisure company with 850 properties and 145,000 employees in more than 95 countries, says an environmental travel policy is being created. Starwood - brands include St Regis and Sheraton - has been working with the Carbon Trust since 2005 on projects that could save the company 32 per cent of its UK carbon footprint.

PwC is another firm working with the Carbon Trust to develop a comprehensive emission reduction plan. Its employee benefits scheme, Choices, offers an online system for employees to search its fleet for green vehicles including those with low emissions and hybrid or biofuel vehicles. Staff can access information on all aspects of green motoring, including taxation, vehicles and offsetting. A "go carbon-neutral" scheme encourages staff to plant enough trees to absorb CO 2 emissions produced by vehicles. So far, 16 per cent of employees have opted voluntarily to offset their emissions via a monthly payroll deduction. The scheme is three years old and more than 1,500 trees have been planted to offset 1,161 tonnes of carbon.

The management board is also championing a personal target of a 20 per cent reduction in air travel across the business. To help achieve this, the firm's top 1,500 business travellers receive quarterly reports on their personal air travel impact.

Companies with an environmental travel policy in place are probably already breathing a sigh of relief, but those that have yet to formulate one are certain to come under increasing pressure - from investors as much as consumers - at least to engage the issue.