Lostprophets sex offender Ian Watkins told a jury how "murderers" went into his cell at Wakefield Prison and forced him to look after a mobile phone.
Watkins told a court how the men were acting on the orders of the jail's 'top boy' in a plot to extort money from the former singer's fans.
The 42-year-old denies the offence, claiming he was forced to have the mobile by other criminals in the prison.
Watkins gave evidence today on the third day of the trial.
He said: "I was in my cell and two guys came. They were known murderers."
The defendant said the phone was thrown onto his bed and he was told he had to look after it.
He continued: "I didn't want to mess with them."
Watkins refused to name the men when asked by his barrister, Gareth Burrows, if he would like to identify them.
Mr Burrows asked: "Why is that?"
Watkins replied: "I like my head on my my body. Sorry to be glib...fear of reprisals."
Watkins then went on describe how he feared he would be killed if he did not look after the phone.
He added: "About an hour later they came back and they told me that they wanted me to get them some revenue streams, or hook them up."
Watkins said the men were referring to his fans and the people who wrote to him in prison.
He said the men returned to his cell a number times over the next few days and ordered him to get in touch with people on the phone.
Watkins said the phone was sometimes taken away from him.
He said: "The threats were constant.
"If I did not sort them out then I was no use to them.
"I knew who the phone belonged to because he was running three phones on the wing. Renting them out, using them himself."
Mr Burrows asked Watkins: "What sort of prisoner was he?"
He replied: "A serious guy - connected. Not a foot soldier. Not a lieutenant. A top boy.
"I'm trying not to say too much."
The barrister then asked: "Why is that?"
Watkins continued: "He's from a proper criminal family. If I say too much people will know who I am talking about.
"He is not someone who gets his hands dirty.
"For a long time previously and after this there were rumours that this guy had members of staff running stuff for him."
Watkins described the potential consequences if he refused to look after the phone.
He said: "Chances are someone would sneak up behind me and cut my throat.
"It's not like one-on-one. Stuff like that, you don't see it coming."
Earlier in the day, Watkins was asked to describe the prisoners he shared a wing with at the maximum security jail.
He said: "Murderers, mass murderers, serial killers, rapists, paedophiles. The worst of the worst."
Watkins said the conditions of the jail's D Wing felt "alien" to him and he was on medication for anxiety and depression.
He said: "Compared to the prison population, I'm not anonymous.
"I guess most people, when they go to prison, they can blend in,
"But everyone has an opinion on me, which is fair enough, and I have to deal with that every day."
Watkins wore a denim jacket with a white collar and jeans and had his hair tied up as he gave evidence.
He used an inhaler on the witness stand shortly before he began giving his evidence.
At one point, Judge Rodney Jameson, QC, told Watkins to keep his voice up so the jury of nine men and three women could hear him clearly.
Watkins looked apologetically at the jurors and said: "Sorry guys."
Asked to describe his music career, Watkins told the court his band had sold between five and ten million records across the world between 1999 and 2012.
He described himself as the singer-songwriter.
Watkins said the Lostprohpets had toured all over the world, headlining at Wembley Arena and the MEN Arena in Manchester.
The trial continues.