An investigation is underway after a business was damaged by fire at Five Dock this morning.

Emergency services were called to the business on the Great North Road about 4.30am (Tuesday 6 September 2016), after a police patrolling the area detected smoke coming from a building.

They alerted Fire & Rescue NSW who arrived and extinguished the blaze, preventing it from spreading to adjoining buildings; however, the shop was extensively damaged.

At this time the cause of the fire is to be determined and, as a consequence, it is being treated as suspicious.

Scene of Crime officers have examined the site and an investigation is now underway into the cause of the blaze.