UK triple murder: Mom to enter plea

Tania Clarence has been in detention for the murder of three of her children.

The London home where Tania and Gary Clarence's three children were killed. Picture: AFP.

LONDON - South African-born murder suspect Tania Clarence is due to enter a formal plea for the first time today after being charged with killing three of her children at the family's upmarket home in New Malden, south London, in April.

The 42-year-old has been in detention for more than 10 weeks after the bodies of the severely disabled children were discovered while Clarence's husband Gary and the couple's eldest child Taya were on holiday north of Johannesburg in April.

Today's hearing at England's Central Criminal Court is expected to see Clarence formally plead on three separate counts of murder.

The former graphic designer had quit her career to care for four-year-old Olivia and three-year-old twins Max and Ben, each of whom had been diagnosed with Spinal Muscular Atrophy, a rare genetic disorder that causes muscle weakness and progressive loss of movement.

The illness rendered the children unable to stand and they required constant attention, which their mother reportedly struggled to cope with.

It's understood the children were killed by suffocation.

A judge later took what he described as an "exceptional decision" to keep Clarence out of prison, citing the extraordinary circumstances of the case.

As a result, the defendant has been held in a secure hospital under the UK's mental health act.