In August 1946, the British began to intern (e.g. illegals) those they caught in camps in Cyprus.  Approximately 50,000 people were detained in the camps, 28,000 of whom were still imprisoned when Israel declared independence on May 15, 1948.

Source: Aharon Cohen, Israel and the Arab World, (NY: Funk and Wagnalls, 1970), p. 174.