SCOTTISH haulage companies may soon register many of their lorries on the continent where fuel and vehicle excise duty are vastly cheaper. They include Greenock-based G & S International, which last night confirmed it has spent #30,000 on research into the likely financial gains from ''flagging out''.

Its final decision on so-called ''plates of convenience'' is subject

to next month's Budget - amid growing fears that Chancellor Gordon Brown will not deliver the tax reforms demanded by hauliers' trade associations.

UK truckers already pay the highest rates of vehicle duty in Europe: #3120 a year for a 38-ton, five-axle lorry, compared with a European average of #1100. In Holland, the duty is just #651. In addition, filling a diesel tank on the continent is at least #100 cheaper than in Britain.

Registering vehicles abroad could save UK hauliers millions, cost jobs, and boost Treasury coffers in Europe. Flagging out is possible by hiring local drivers or via the simple expedient of UK truckers paying their income tax in Europe by citing new ''domiciles'' - which could be their cabs - based on the continent.

There are clear signs that hauliers are not scaremongering by playing the foreign card:

n The Road Haulage Association's Scottish regional director, Phil Flanders, yesterday confirmed it is offering advice to firms interested in ''flagging out''. He added that an undisclosed number are already ''way down the road'' of doing so;

n One of Britain's best-known road haulage companies - Eddie Stobart Ltd, of Carlisle - announced at the weekend it is ready to register up to one-quarter of its massive fleet abroad, and:

n Mr George Brown, a partner in

G & S International, declared: ''We are serious about such a move . . . we are fed up to our back teeth over

Government failures to recognise our tax problems.''

Like many others Scottish firms, he has also suffered from ''cabotage'' - increased competition from continental rivals now allowed to work wholly in the UK.

They can undercut British haulage charges because of lower fuel and vehicle duty costs, let alone cheaper purchase prices for trucks and spares in Europe. Vehicle technology is such that the continental truckers can fill up in Calais, drop in Aberdeen - and return to France - on one tank of fuel.

Mr Brown's firm already buys 80% of its fuel in Spain, spending about #65,000 a month but saving more than #100 on every 1000 litres purchased. ''We need reform,'' he said. ''I work in the Common Market, but the Government's tax policy on vehicle excise duty and fuel is such that we are not able to compete on a level playing field.''

Today, UK truckers will lobby Parliament in a ''Thousand Man March'' to highlight industry concerns over the swingeing taxes on their commercial vehicles. Different sectors of the road transport industry will join the protest, which threatens horrendous traffic jams in London if organisers' appeals to demonstrators to leave lorries behind and walk to Parliament and Downing Street are ignored.

Raised diesel prices in the Budget could cost some 53,000 jobs in the industry and related distribution and fuel sectors by the year 2002, according to the Freight Transport Association and Road Haulage Association. Both want at least a freeze on the present rate of diesel duty, and the introduction of compensation arrangements for essential goods vehicle operators.

Meanwhile, Scots firm Maxi Caledonian Holdings, of Irvine, warned the Scottish economy - and customers - will suffer if road and fuel taxes are increased in March. Chairman Gerry Atkinson argues: ''Margins are already so tight in the haulage industry that all we can do is put our prices up to cover increased costs if we want to stay in business.

''Scottish customers will be hit more than elsewhere in the UK because more miles are involved in reaching them.''

Mr Atkinson, whose firm operates 130 vehicles mainly from English depots, adds: ''The increasing cost of haulage will have serious adverse effects on Scottish-based industry.''

The Road Haulage Association agrees. Spokesman Don Hodges says: ''Knock-on effects of further tax increases will be worse in Scotland than elsewhere, from delivering raw materials to manufacturers to food in shops.''

A proposed working-time directive for the industry will also see costs ''go through the roof'', according to Mr Atkinson.

Significant changes in work practices will have to be introduced once working time is restricted to eight hours. Truckers would not even be able to drive from Bellshill to Manchester and back within legal hours, which is currently possible under shift times of up to 12 hours.

Hauliers will have to introduce expensive changeovers - or a series of short runs, increasing the number of trucks on the road and, it is claimed, perhaps doubling the driver workforce with associated costs.

Hauliers yesterday criticised fuel duty rises of between 3% and 6% above the inflation rate by various UK governments, and warned any repeat next month will do enormous damage to their competitiveness and, in turn, the economy. But some 90% of freight still goes by road because viable rail and sea alternatives have not yet been developed.

There are few signs of an early improvement, according to the Scottish Transport Studies Group's review of transport published this week - its last before elections to the Scottish Parliament. One study in particular warns that a network of piggyback gauge routes in Britain is ''unlikely to become reality in the foreseeable future''.

It acknowledges that upgrading the West Coast Main Line for piggyback would open up the European network to Scottish industry to carry lorry trailers on rail wagons. However, it questions the wisdom of creating one single, 500-mile-long route because customers might be reluctant to commit themselves unless a reliable service is guaranteed in the absence of a diversionary route should infrastructure or train failures arise.

The report concludes the future for piggyback looks better than ever, but adds: ''There is still much work to be done to ensure the opportunities that are available are not lost through the provision of a poor service that does not meet the demands of modern day industry.''