The federal government has turned away thousands of people aspiring to a life in Australia by abolishing a group of visas and telling would-be residents their applications never existed.

About 16,000 people including families are affected by the decision. Many of them have waited eight years for a response and migration agents say some are now too old to apply for other visas.

In one of her last acts as assistant immigration minister last week, Michaelia Cash ruled that an annual cap of 284 places for three types of skilled migration visas had been reached, and all outstanding applications "are taken not to have been made", or cancelled without a trace.

Senator Cash was promoted to Minister for Employment and Minister for Women by Prime Minister Malcolm Turnbull last week.