Convenience shop owner Adeel Khan only fabricated a story of three armed men who tied him up and set fire to his Rozelle store after he discovered three innocent people had died, the prosecution says.

Mr Khan is accused of setting fire to the Darling Street building after setting up containers of petrol linked by fabric throughout the store in an attempt to destroy it. Three residents who were asleep either upstairs or next door to the building - Chris Noble, 27, Bianka O'Brien and her baby son Jude - were killed in the resulting explosion and fire.

During cross-examination of Mr Khan on Tuesday, Senior Crown Prosecutor Mark Tedeschi QC said the 46-year-old failed to mention the three men he claims held him hostage for five hours to any emergency services or health worker in the immediate aftermath of the fire and explosion.

Mr Khan, who has pleaded not guilty to a string of charges including three counts of murder, told the jury he can't recall much from the time of the explosion at 4am on September 4, 2014 until he woke up in intensive care following surgery on September 5.

Mr Tedeschi put to Mr Khan that "you made it up as you went along in the police interview".

Mr Khan began tearing up as he replied, "I did not".

"I suggest you didn't mention at the scene to the ambulance officers or at the hospital anything about these three men or these vicious criminals that kept you prisoner." Mr Tedeschi said.

"Correct, sir," Mr Khan replied.

"I suggest you didn't say anything about three men until after you knew three people had died," Mr Tedeschi said.

"I can't remember the sequence of these things," Mr Khan replied.

"I suggest you made up the story about the three men to evade responsibility for the three deaths that you had caused," Mr Tedeschi said.

"I disagree," Mr Khan said.

The force of the explosion saw Mr Khan buried under debris and a commercial fridge and he had to be rescued by fire and rescue officers.

Earlier in the trial Mr Khan admitted saying "I'm so sorry" to a paramedic several times but but denied saying "I didn't mean it".

He said he was expressing his relief at having survived and was saying thanks to the emergency services workers.

But Mr Tedeschi said the apology was actually "because the explosion and fire were more serious than you expected".

Mr Khan disagreed.

Mr Tedeschi put to him that he intended to light a fire big enough to destroy the shop - and thereby release him from a five-year rent agreement and associated equipment leases - but he didn't intend to cause such a damaging explosion.

"I disagree, sir," Mr Khan said.

Mr Khan denies responsibility for the explosion and fire. He claims a trio of robbers tied him up in a storage room and blindfolded him for about five hours before the blast. He says they set up an elaborate network of petrol-filled containers and fuel-soaked wicks around the shop.

Investigators were unable to find people matching Mr Khan's descriptions of the robbers in surveillance footage, the court has heard previously.

The trial before Supreme Court Justice Elizabeth Fullerton continues.