Stan Mallon claimed he had a vision

They feel he received a lenient sentence after admitting a child sex offence.

Mallon received a 21-month jail sentence in March, but now the US District Attorney's Office in Chicago has filed a notice of appeal with the court.

The prosecution had argued for a 51-month sentence.

Mallon admitted using an internet chatline to contact a girl called "Marny" who turned out to be an undercover FBI agent.

The 62-year-old was acting chief executive of the Ulster-Scots Agency until his arrest last March in Chicago.

He escaped the maximum sentence of more than four years in prison after the judge ruled he was suffering a "diminished capacity".

The father of five from Crumlin in County Antrim told the court he was hallucinating when he used the internet chatline in February last year.

'Persuaded by vision'

He sent the "girl" 17 emails in 24 minutes and claimed to be a rich 42-year-old president of a biotech company.

Mallon was arrested in Chicago after arranging to meet her in his hotel room while on his way to a conference in Washington.

I am concerned at the timing of this announcement and the motivation behind it Kevin Winters Solicitor

Judge Joan Gottschall at the US District Court in Chicago ruled his behaviour was an "aberration" from his otherwise law-abiding life.

Mallon said his hallucinations led him to believe his son-in-law had appeared to him and told him to contact the girl, the court heard.

The prosecutor's office has 60 days to submit the paperwork, but it is known it disagrees with the judge on matters of law and characterises its appeal as "a reaction to her sentence ruling".

It can take more than six months for an appeal to be heard, however it could be fast-tracked because Mallon is scheduled for release before the end of this year.

Mallon's Belfast-based solicitor expressed concern that the sex offender's sentence was to be challenged by US authorities.

In a statement, Kevin Winters said he was concerned "at the timing of this announcement and the motivation behind it".

He said any attempt to increase the sentence would be strenuously challenged.