Two more people have been arrested in connection with the murder of a 19-month-old girl following an arson attack on Saturday.

The 19-year-old man and 41-year-old woman, both from Paddington, were arrested yesterday on suspicion of murder and perverting the course of justice.

Toddler Siariah Letang from Thornton Heath was killed after flames tore through her grandmother Brenda Ricketts’ first-floor maisonette in Camberwell on Saturday.

She died of carbon monoxide poisoning due to smoke inhalation, according to the results of a provisional post mortem examination carried out at Great Ormond Street Hospital yesterday.

Her 11-year-old aunt Shakira Jackson remains in a critical condition in hospital following the fire, which was started as the family slept.

Siariah’s mother Ellisha, 23, four-year-old brother Cameron and 40-year-old grandmother are described as being in a serious but stable condition.

Officers have been given a final extension to question a 27-year-old man and a 28-year-old woman, who have been in police custody since being arrested on Saturday evening.

Police can only detain people for up to 96 hours under UK law before they must be released or charged.

Officers are preparing to hand over evidence gleaned from their investigation to the Crown Prosecution Service this afternoon, who will decide whether there are grounds to bring any charges.

Acting Detective Chief Inspector Rick Murphy from the Homicide and Serious Crime Command said: “This fire has wrecked the lives of those involved and I am appealing to anyone who may have witnessed this incident to contact us and help piece together what happened.

“Were you in the area of Arnould Avenue in the early hours of Saturday morning, particularly from around 4am to the time of the incident?

“Did you see anyone acting suspiciously or notice any vehicles unusual to the area?

“If you have any information, no matter how small and insignificant it may seem, please call the investigation team on 0208 721 4868.”

* Police previously stated Siariah was two years old, but this has since been corrected by NHS staff.