An Indian policeman who was mentally unfit to stand trial for strangling his young wife just two weeks after he arrived in Britain has pleaded guilty to her manslaughter.

Harjinder Pal, 39, killed 21-year-old Kulvir Kaur in February 2009 because of his "delusional" belief that she was cheating on him, the Old Bailey heard.

He was ruled unfit to stand trial in June 2010 and sent to a mental hospital indefinitely after a jury found he carried out the act of killing his wife.

But after four years of treatment, a doctor ruled Pal was now fit to enter a plea and today admitted the manslaughter of Ms Kaur on the grounds of diminished responsibility.

The court heard Pal still held the "ongoing delusional belief about his wife's infidelity" as he continued to suffer from a "depressive disorder with psychotic symptoms".

He was detained indefinitely under a hospital order after Judge Richard Hone QC said he remained a "significant risk" to the public.

Dressed in a dark suit with a shirt and tie, Pal sobbed throughout the hearing and was joined in the dock by a Punjabi translator, two security officers and five health workers.

The victim's brother and father were in court to hear the sentencing.

Judge Hone told Pal: "You became obsessed with the delusional belief that the victim was having a relationship with other men.

"These delusional beliefs were completely, utterly and totally as a result of your mental illness. You killed the person you loved.

"It's astonishingly unhappy to have a young life snuffed out."

Judge Hone said that while there has been an improvement in Pal's condition to "a moderate extent" over the last four years, there remained a "significant risk to any future sexual partners".

He added: "Your tearful appearance in the dock may indicate to those close to Kulvir that you have started to show some remorse for the simply awful act you committed."

Prosecutor Bobbie Cheema QC told the court Pal strangled his wife with a ligature on February 28, 2009, in the house they shared with the defendant's brother in Southall, west London.

Pal dialled 999 just after midday and told an officer he had "murdered" his wife, Ms Cheema said.

Police arrived to find Ms Kaur's fully-clothed body in bed, with the covers pulled up to her neck, and red marks around her throat. Pal also told officers he had eaten from a jar of rat poison found in the bedroom, the court heard.

The couple had entered into an arranged marriage in India in October 2008 before she returned to Britain alone while he obtained a visa. Pal arrived in the UK on February 13 2009 - 15 days before he killed his wife, the hearing was told.