The fire began at AD's Cafe on Brierly Street before 4am, but firefighters responded quickly, and managed to contain the flames to the kitchen.

Damage to the dining area of the cafe was avoided, however, the blaze wrecked the kitchen, leaving appliances, pots and other utensils a blackened mess.

Forensic officers, criminal investigations detectives and uniformed police were at the scene of the fire yesterday, and are still investigating the cause of the blaze.

Anthony Curtis & Co Chartered Accountants principal Tony Curtis had been the first to call emergency services to the fire yesterday.

The fire alarm in his office, which sits directly above AD's Cafe, sounded and he went to investigate about 3.50am.

''The smoke alarms were activated last night, so I came down here just to sort it out,'' Mr Curtis said.

''This place was all full of smoke, so I called the fire brigade, and we could then see flames down there in the kitchen.''

He had called triple-0 and said firefighters had arrived within minutes.

''It was only getting started, so it was just contained in that kitchen area there,'' he said.

''They just gave it a blast and it only took a couple of minutes to put it out.''

He said he saw no one else at the scene while he was there.

The smoke in the accountant's office dissipated, and Mr Curtis said his business was not otherwise damaged.

Police have estimated the repair bill for the cafe at $100,000.

They had spoken with the owner of the cafe yesterday morning.

The fire is the second suspicious blaze in the ACT in as many weeks.

A suspected arson attack nearly destroyed a Mitchell brothel on New Year's Day.

It was later revealed that the brothel had not been licensed, an accelerant had been used, and the fire had been started from inside the premises.

Police are continuing to investigate the Mitchell brothel fire.

They are also calling for witnesses to the fire at AD's Cafe to contact Crime Stoppers on 1800333000, or through the Crime Stoppers website.