Stand by for a spate of dental appointments among senior figures in City law firms.Relaxation of the regulations governing multinational partnerships means that US law firms in London are now able to compete for work traditionally done by domestic lawyers.

As a result, a number of US firms with offices here are aggressively recruiting solicitors from City firms - and are prepared to pay for it.One self-styled 'visionary US law firm' is advertising earnings of up to £400,000 to a ttract lawyers in property finance, corporate/commercial and insurance/reinsurance.

Others are not being quite so up front about advertising potential salary levels, but are expected to be offering similar packages.With figures like these being bandied around, a number of City lawyers whose seniority (and earnings) would normally rule them out from switching firms are expected to jump ship.According to those in the know, equity partners at top City firms may be earning only around a quarter of the £400,000 figure being talked about by US firms.

However, the earnings being offered are likely to be comparable with those enjoyed already by senior figures at a handful of the very top firms.Needless to say, only the creme de la creme need apply.

Nicholas Robbins, partner at recruitment agency Garfield Robbins, says: 'US firms are looking for names.

They want named people who will bring in the business.' The Americans believe that if they can attract heavy-hitters who already have a following, these lawyers will bring business with them.

Mr Robbins adds that paying £400,000 may seem a premium in London terms, but not compared with New York salaries.

Angus Mackenzie, consultant in the legal division at recruiters Robert Walters, says the Americans will be interested in people from a very limited number of firms only.

'The lawyers in demand will be those from the top ten UK firms, because of the quality of work that they do.

That is not to say they would not pick someone from outside the top 20, but it is likely to be very rare.

US firms have not heard of firms outside the top 20,' he says.Those outside this elite may be in with a chance if they have a particularly specialist niche practice or some other skills which set them apart, such as being fluent in Russian, he adds.Mr Mackenzie says the areas of work in demand are likely to include company and commercial, project finance, venture capital, capital markets, and banking.

Litigators are not likely to be in demand ('US firms tend not to do litigation in London') and those in commercial property.City insiders are keen to point out that money is not the only lure.

Some of those who make the move may already be earning comparable salaries, says Mr Robbins.

'These are not the sort of people who would necessarily leap around at winning the pools,' he says.

Nevertheless, they may be attracted by the prospect of doing similar quality work but in a far smaller outfit.

US firms would typically have no more than a dozen partners at their London offices.

The work is likely to be international, with greater opportunities for travel.Lawyers may also be attracted by the US way of doing things.

'US firms tend to take more risks.

They are possibly more ambitious than UK firms, more willing to open up satellite offices and push ahead,' says Mr Mackenzie.Individuals may find it easier to shine and be rewarded accordingly, away from the 'dead men's shoes' approach that still prevails at some UK City firms.

Indeed, this is an aspect which is stressed in the 'visionary' firm's recruitment advertising.

Lawyers are rewarded through a system which 'owes more to merit and general contribution than it does to seniority', it says.Observers are divided over what will be the impact on salaries at UK City firms.

Some are predicting that there will be an increase, as UK firms will inevitably have to try to match what is being offered by the Americans.

However, Richard Chaplin, chief executive of recruiters Strategic Marketing, does not believe that there will be much of a knock-on effect.

The n umbers of people being wooed are likely to be too small and too select, he says.Mr Mackenzie agrees.

'I do not think this will have a massive bearing.

If there was going to be a great big flood of people from London law firms, it would have to be addressed.

However, for the time being, UK salaries will continue to be judged against themselves, rather than against American salaries.'But isn't recruitment at this level all done by word of mouth rather than through answering ads, anyway? Can anyone really envisage senior City lawyers surreptitiously phoning up for an application form during their secretary's lunch hour, or staying late at the office to photocopy their CV?Mr Chaplin reckons that a maximum of 30 people would fit the bill.

Of these, probably 20 could be eliminated as not being interested.

That leaves just ten likely candidates.

Law firms do not advertise in national newspapers simply to reach ten individuals who could easily be contacted direct, he says, but for other reasons.

'I do not think the immediate intention is to recruit staff.

It is the firm making the statement that it is serious about developing its presence in the UK.'Mr Mackenzie agrees that there are many reasons for advertising in this way, particularly for including stratospheric salary figures.

'It creates awareness and gets people talking.

Big American firms like to announce themselves in a rather unquiet way.

They are very gung ho.'It is also, he adds, a highly effective way of 'putting the wind up the UK legal fraternity'.