The number of Kolpak players in county cricket could be set for a drastic reduction after the European Union decided on a new interpretation of the employment law that has brought about a huge influx of players from South Africa and the Caribbean.

Under the rules of the Cotonou Treaty, free trade exists between the European Community and many African, Pacific and Caribbean countries, and in 2004, the Czech handball player, Maros Kolpak, won a ruling from the European Court of Justice which allowed him to play professionally in Germany without be classed as a foreigner.

That set a precedent that has had a major impact on English cricket, with players such as Jacques Rudolph, Martin van Jaarsveld and Omari Banks choosing to ply their trade in England rather than seek international honours for South Africa or West Indies.

A similar situation exists in French rugby union, which has up to 150 South Africans on its books, and as a result, a campaign was launched by the Central Council of Physical Recreation. It has resulted in the EU, under French presidency, ruling that the Cotonou Treaty was designed for the free trade of goods and services and should not be regarded as free movement of labour.

It promises to be a significant development in the ECB's battle to reduce the number of Kolpak players in county cricket, and a spokesman said: "The ECB have noted the recent developments and are looking at the possible implications of that."

One possible upshot would be for existing Kolpak players to be permitted to complete their existing contracts, but for future signings to be regarded as overseas players.