(Australian Associated Press)
* The 457 visa program allows business to employ foreign workers for a period up to four years in skilled jobs where there is a shortage of Australian workers.
* The numbers are uncapped and there is no limit on the number of times they can travel in and out of Australia.
* Foreign workers can bring their families to work or study.
* Employers must apply to sponsor a 457 worker or enter into a formal labour agreement with the government.
* They must show they are training locals.
* As at September 30 there were 95,757 workers in Australia on primary 457 visas and 76,430 secondary visa holders (members of their family).
* But numbers are in decline – in March there was a 9.2 per cent drop in primary 457 visa holders compared to 2015.
* In July 2013 new laws came into effect, including giving Fair Work Australia the power to investigate breaches of the system.
* Labor wants jobs to be advertised locally for at least four weeks before a foreigner is sourced.