The bill was signed by Mbeki at 18:00, presidential spokesperson Bheki Khumalo said. Khumalo said the new law would come into operation through proclamation which was being drafted by the department of home affairs.
Speaking in the National Assembly on Wednesday, Mbeki admitted that the controversial bill approved last week by Parliament might not be sufficient to help attract the skilled foreigners South Africa needed.
It is estimated that South Africa has a shortage of between 200 000 and 500 000 skilled workers.
Mbeki said the government was open to suggestions regarding changes to the legislation. The National Council of Provinces last week passed the controversial bill, which all political parties agreed was severely flawed. The National Assembly approved it one week earlier.
Home Affairs Minister Mangosuthu Buthelezi piloted the bill through Parliament and to his chagrin saw it radically redrafted by the African National Congress during the parliamentary committee stage.
Critics have argued that the quota system, which was part of eleventh-hour amendments introduced by the ANC, could hinder the import of skilled persons.
This view was shared by Trade and Industry Minister Alec Erwin who, after the bill was adopted by the Assembly, called for the quota system to be amended by the NCOP.
However, this was not possible because of the June 2 constitutional deadline for a new immigration law on the statute books, or for an amendment of the current Aliens Control Act.
The ANC then agreed it would ask Buthelezi to introduce amendments as soon as possible once the law was promulgated.