The huge Vegas-style casino resort will create at least 120,000 jobs and provide a massive boost to the regional economy and that of the town of Alcorcón, where it will be based – but US tycoon Sheldon Adelson has demanded a series of privileges in exchange.

These include exemption from taxes such as IBI (property tax), income tax and gambling tax; changes in the Workers' Statute to make it cheaper to employ people; changes to foreign affairs legislation so that they can take on employees from other countries; complete freedom of opening hours; relaxing of smoking laws to allow lighting-up in the casinos; allowing under-18s to enter the gambling areas - since they may have to cross through them to get to their hotels or other leisure facilities, and parents may need to take their children with them if they go into the casino areas; and the law preventing gambling addicts from playing to be eliminated.

When negotiations began for Eurovegas to be based in Spain, the then president of the region of Madrid, Esperanza Aguirre, said 'any rules that have to be changed will be changed'.

A legitimate entity known as a 'legal and fiscal island' may be created to allow Eurovegas to break the rules.

But some legislation has already been modified to apply to everyone – casinos used to pay between 22 and 45 per cent tax on their income, but a law passed in December means once Eurovegas is opened they will all only pay 10 per cent.

The region has also changed the law so that the owners of any business can decide what days and times they wish to open.

So far, they have refused to relax the rules to allow under-18s in the gambling areas, although say they are negotiating with the central government about letting customers smoke at least in the casinos – even though these are enclosed, public areas.

But minister of health Ana Mato and the central government's vice-president, Soraya Sáenz de Santamaría, have both stated categorically that they have no intention of amending this law and that it is not even up for discussion.

Neither is is likely that the Workers' Statute will be amended, although Madrid's regional government says Rajoy's labour reforms have already leant towards Adelson's requests in any case.

A new metro station at Eurovegas, and more frequent buses running to Alcorcón are among the additional transport infrastructure planned for the complex.