LONDON - British pop star Joss Stone on Tuesday told the trial of two men charged with planning to rob and kill her that she was unaware of the plot until police visited her after they had been arrested.

The 25-year-old singer said: "Apart from someone (police) coming around to say someone is trying to kill me, it was a really nice day."

Stone was giving evidence at the trial of Kevin Liverpool, 35, and Junior Bradshaw, 32, who deny charges of plotting to rob and kill her before dumping her body in a river in June 2011.

The singer also said she routinely leaves her front door open at her rural home in Devon, southwest England.

Exeter Crown Court heard that the pair were arrested a few miles (kilometres) from Stone's home, with an arsenal of weapons - including a samurai sword, hammers and a metal spike - in the boot of their battered car.

Stone was at home at the time but said she was only aware of the incident when police contacted her later that day.

The star admitted that before the plot she had lax security and rarely locked her front door.

"I've lived in Devon for a long time and nobody really shuts their door," she said.

Stone said: "I had an alarm but I did not really turn it on very much.

"I didn't really have a lock on my door... But I do now."

She described the property, accessed by narrow country lanes, as an "open house" for family, friends and her then-boyfriend.

The court heard that the two defendants were arrested at around 9:00 am after driving slowly a few miles from the singer's home where they stopped a postman and showed him a small photograph of Stone.

Policemen had earlier spoken to them in the city of Gloucester after their vehicle was severely damaged when it collided with railings and a stationary digger as they drive out of a motorway fuel station.

Handwritten notes found in their possession described Stone as a "she-devil", and referred to a plot to "decapitate" her.

It is unclear how the men knew she would be at her house on the day they allegedly intended to attack her, but Stone said some people wanting to know whether she was at home or not might "put two and two together" with the help of her published concert dates.

The prosecution says Stone was a target because two months before the men were arrested, she had been a guest at the wedding of Prince William and Kate Middleton.

Stone has sung for the royals at charity concerts. Of why she was invited, she said: "I don't know. I guess they just invited me because they thought it was nice to invite me."

The trial is expected to last up to three weeks.