Australia is tightening English language requirements for foreign students in what it said on Thursday is a bid to improve standards across the country's Aus$28 billion ($22 billion) international education market.There are more than 550,000 international students in Australia, according to government data, which lists the lucrative sector as the country's third-largest export earner. Currently, prospective overseas students can take an intensive English course to prepare for further studies if they do not already have other qualifications showing their ability to study in the language.Now they will also have to take a new official test of their language skills before they can start such university or vocational studies to ensure they have reached the required standard, said Education Minister Simon Birmingham. "The vast majority of language courses are providing high quality outcomes... but some slip through the cracks and it's unacceptable for that to occur," Birmingham told reporters.No details were provided on what the test would include, but Birmingham said its standard would be enforced by the national education regulator. He added he did not believe the measure would hurt international student numbers but would instead strengthen the integrity of the education system, making it more appealing to potential arrivals.Some 16 per cent of the country's international enrolments are for pre-studies language courses, according to July figures from the education department. The top three nationalities enrolled in pre-studies language courses are Chinese (27 per cent), Brazilian (12 per cent) and Colombian (8.7 per cent).