A coroner has strongly criticised an attempt by lawyers for the former Welsh first minister Carwyn Jones to have evidence about allegations of sexual misconduct by politician Carl Sargeant heard at his inquest.

Sargeant, 49, was found dead at his home in north Wales on 7 November 2017, four days after he was sacked from his job as cabinet secretary for communities and children amid claims of inappropriate sexual behaviour towards women.

His widow, Bernie Sargeant, has told the inquest that she had questioned her late husband about the allegations and believed that he was innocent. She also said she had no knowledge of any previous allegations apart from one anonymous letter dating back to 2014.

On Wednesday, Cathryn McGahey QC, representing Jones, made an application to call evidence from the former Flintshire county council leader Aaron Shotton that she claimed could contradict evidence given by Bernie Sargeant.

She said: “Our submission is that [her] evidence may not have been complete or fully accurate.”

McGahey said a statement from Shotton suggested another anonymous letter had been received. She said Shotton claimed that in early 2017 he was told that Sargeant had received an anonymous letter making allegations about him being seen in a pub beer garden with a woman.

Shotton also said in the statement that an alleged incident involving Sargeant had occurred at the evening reception of Shotton’s wedding, although he said he had not witnessed it, the inquest was told.

McGahey said the evidence could be key to the “credibility and reliability” of Bernie Sargeant’s evidence and could provide information about what “incidents or allegations may have been preying or were preying on Mr Sargeant’s mind” at the time of his death. She asked for Shotton to be called to give evidence.

Leslie Thomas QC, for Bernie Sargeant and Sargeant’s son Jack, said he did not believe the allegations were relevant. He said: “The deceased person is not here to defend themselves. This is not a trial; there has been no investigation into these rumours and suspicion.”

The coroner, John Gittins, said he was “surprised” by the application as he had twice ruled that Shotton’s statement was not relevant to the inquest, a decision that had been upheld at appeal.

He said he was “astounded” McGahey had suggested there must have been something in the pub garden incident because someone had written an anonymous letter about it.

Gittins said he believed Bernie Sargeant had answered fully. Describing the application as “opportunistic”, he added: “It does not advance my inquiry.”

The coroner said Sargeant’s state of mind when he died was relevant. But he said it was enough to know that allegations had been made. “This is not a trial. This court is not required to look into the truth of these allegations,” he said.

Gittins read out statements from the first minister, Mark Drakeford, and the Labour party in which they said lessons had been learned since Sargeant’s death.

The inquest at Ruthin in Denbighshire continues.

In the UK, Samaritans can be contacted on 116 123 or email jo@samaritans.org. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In Australia, the crisis support service Lifeline is 13 11 14. Other international suicide helplines can be found at www.befrienders.org.