Ian Watkins, the former Lostprophets frontman jailed for sexual offences involving children, has been given another 10-month sentence for possessing a mobile phone while in prison.

The 42-year-old had denied the charge, claiming that two inmates had forced him to hold on to the device so they could contact women who sent him fan mail and use them as a “revenue stream”.

Watkins, who jurors were told was serving a sentence for sexual offences, refused to name the men. “You would not want to mess with them,” he said.

He said his fellow inmates at HMP Wakefield in West Yorkshire were “murderers, mass murderers, rapists, paedophiles, serial killers - the worst of the worst”.

Watkins was jailed in 2013 after admitting 13 sexual offences which the judge said “plumbed new depths of depravity”. They included the attempted rape of a baby. He was sentenced to a 29-year prison term followed by an additional six years on licence.

During a five-day trial at Leeds crown court, which concluded on Friday, the jury heard how he was strip-searched in jail in March 2018 after a woman called and said she believed he had been talking to her on a prohibited mobile phone.

Prosecutor Stephen Wood said the phone, a small GTStar, had been used to contact Gabriella Persson, who jurors were told had previously been in a relationship with Watkins but had stopped contacting him in 2012.

Wood said she began to be in touch with him again in 2016 via phone calls, letters and legitimate prison emails. Persson told jurors she had received a text in March 2018 from a number she did not recognise which just said: “Hi Gabriella-ella-ella-eh-eh-eh”.

She said the message, a reference to the Rihanna song Umbrella, made her think that Watkins was contacting her and she phoned the number to confirm it was him.

Wood said Persson had reported Watkins’ use of the phone, and that the prosecution should reject his claim that he had been forced to keep hold of it.