Cape Town, South Africa: South African cricket was rocked Thursday when fast bowler Kyle Abbott and one-day star Rilee Rossouw quit the national team in order to play county cricket in England under so-called 'Kolpak contracts'.

Here, AFP Sports explains Kolpak agreements:

-- The Kolpak ruling came into force in 2003 when the European Court of Justice ruled that anyone with a work permit from a country which has an associate trading agreement with the EU had the same rights as a European worker.

-- The ruling originally related to Slovakian handball player Maros Kolpak who was released from his German club because of a quota on non-EU players. He claimed it was unfair and the court ruled in his favour.

-- A player becomes eligible for a Kolpak deal when he gives up the right to play for his country, and is not classed as an overseas-player signing.

-- Kolpak players need only a working holiday visa to play.