The UK government's most senior adviser on Scottish law has denied professional misconduct after he was convicted of a firearms offence.

Lord Richard Keen QC, Advocate General for Scotland , faces allegations of behaving in a way that was "likely to diminish the trust and confidence which the public places in a barrister or in the profession".

The professional charge comes after Lord Keen, a former former chairman of the Scottish Conservative Party, was fined £1000 in 2017 after pleading guilty to failing to secure a shotgun, which he held a valid licence for.

The offence came to light after police attended Lord Keen's home in Edinburgh, after reports of a suspected burglary while he and his wife were away on holiday.

While investigating the break-in, officers found an unsecured 12-gauge shotgun in a bag in the basement.

Lord Keen appeared at a Bar Tribunals and Adjudication Service (BTAS) hearing on Tuesday where he denied professional misconduct.

Tom Forster QC, representing the Bar Standards Board, said Lord Keen had failed in a core duty of being a barrister by being convicted of the criminal offence which carries a maximum sentence of six months in prison.

Mr Forster said: "I submit and it brings me no great pleasure to do so, that Lord Keen did breach the core duty. "First, it is plain that breach of a condition of a shotgun certificate is not a minor criminal offence.

"It may not be a serious criminal conviction but that is not to say it is a minor criminal offence."

The allegation, he said, was not about Lord Keen's integrity or honesty but his "carelessness" with the shotgun which put the public at risk.

Mr Forster said: "The gun was being kept in a residential property in an urban area therefore there was a heightened obligation to Lord Keen to ensure it was kept securely."

The tribunal heard Lord Keen had used the shotgun on December 27, 2016 and forgot to return the gun to a locked safe before going on holiday.

He was accused of having a "lacking attitude" to gun safety and Mr Forster argued that housebreakers, including potential burglars, could have accessed the weapon.

He added: "There is no real substantial reason than 'I forgot'.

"It simply just won't do in these circumstances."

Lord Keen has featured in a number of high profile cases and has represented the Prime Minister at the emergency Supreme Court hearing in September over the suspension of Parliament.

Lord Keen, who is also the Ministry of Justice spokesperson for the House of Lords, was made a life peer in June 2015.

He was appointed as Advocate General for Scotland in May 2015 and then stepped down as chairman of the Scottish Conservative Party.

However it was said that Lord Keen is held by the same standards as all members of the Bar Standards Board. Mr Forster continued: "It's a factor who he is but that does not mean he is treated differently than any other barrister.

"He can't be held to a higher standard than anyone else who is a member of the bar of England and Wales."