Three people were hospitalised after the vehicle - owned by Hari Om Transport - ploughed through a McDonald's car park at Fairy Meadow near Wollongong on Monday.

The company's fleet was later inspected by authorities, who found all 10 had defects - including bald tyres, brake issues and inoperable seatbelts.

Allegations have since been raised that a number of the company's drivers are student visa holders working more than allowed, according to Macquarie Media.

People on students visas can work up to 40 hours a fortnight during university semesters.

Asked about the claims on Sydney's 2GB radio on Thursday, Home Affairs Minister Peter Dutton said he has asked Australian Border Force to investigate.

"If they aren't abiding by the law there'll be consequences," he said.

"In some cases, people will have their visas cancelled (and) they'll leave the country."

Employers could also be charged with exploiting workers or acting outside the law, he said.

The NSW Transport Workers Union said it had also received claims of student exploitation and was looking into the matter.

"We're going to do some inspections with this company and the companies they purport to contract to," state secretary Richard Olsen told 2GB.

"We're going to go right up the chain to see exactly what has occurred."

NSW Police are still investigating the crash.

Australian Associated Press