Sydney Airport emergency: United Airlines flight UAL830 suffers 'mechanical issue' after take-off - firetrucks on the tarmac

A United Airlines flight from Sydney to America was diverted back to Sydney Airport following a mid-air emergency.

Flight UAL830 left Sydney Airport shortly after 12pm on Monday and began its journey to San Francisco when it suffered a suspected mechnical issue.

The Boeing 777-300 plane turned around a short time later and landed in Sydney at 2.34pm - a little over two-and-a-half hours into its trip.

Firefighters met the plane on the tarmac.

United Airlines flight UAL830 (pictured) from Sydney to the United States was diverted back to Sydney Airport following a mid-air emergency

United Airlines flight UAL830 (pictured) from Sydney to the United States was diverted back to Sydney Airport following a mid-air emergency

Flight UAL830 (pictured) landed safely in Sydney after suffering a suspected mechanical issue shortly after take-off

Flight UAL830 (pictured) landed safely in Sydney after suffering a suspected mechanical issue shortly after take-off

All 167 passengers disembarked the plane safely.

In a statement to Daily Mail Australia, United Airlines said the plane was diverted to Sydney 'due to a maintenance issue'. 

'The plane landed safely and passengers deplaned normally at the gate,' it said.

'We are providing accommodation overnight for passengers and rebooking them to San Francisco tomorrow.'

Passengers disembarked the plane safely (pictured) once it landed back at Sydney Airport

Passengers disembarked the plane safely (pictured) once it landed back at Sydney Airport