A man arrested in Johannesburg on Friday who is suspected of murdering his wife and two daughters in Britain ​bought an unlicensed gun, possibly to kill himself, South ‌African police said.

Ndodana Mkhanyisi Tshuma, 45, a British citizen of Zimbabwean heritage, appeared in a Johannesburg magistrate's court on Monday and was remanded in ​custody until July 22, for authorities to establish whether ​he is in South Africa legally.

He has been charged ⁠in South Africa with illegal possession of a firearm, which ​carries a potential 15-year prison sentence for first-time offenders, while ​the court will also consider whether he should be extradited to Britain.

British prosecutors have authorised police to charge Tshuma with three counts of murder, after ​the bodies of his wife, 42, and daughters, 15 and ​5, were found at their home in Bedfordshire early this month.

Tshuma left ‌Britain ⁠via Heathrow Airport before the bodies were discovered, South African police said.

"According to our investigation, after landing in South Africa on July 5, he then went to one of the townships and ​he bought this ​particular unlicensed ⁠firearm," South African police spokesperson Athlenda Mathe told reporters.

"It is our suspicion that this ... firearm was ​going to be used to end his life."

South Africa had received a provisional extradition request from Britain but was awaiting the full document, Mathe added.

She said Tshuma had family in ⁠South ​Africa who helped police apprehend him. "His family ​did not harbour him. ... They played a very pivotal role," Mathe said.