Roy Keane has become embroiled in another legal tussle, this time by starting a lawsuit against the bookmaker Paddy Power for mocking him up as William Wallace from the film Braveheart on a match-day billboard last month.

The Republic of Ireland assistant manager has hired A&L Goodbody, one of the State's biggest law firms, to represent him in the case.

Paddy Power has hired Arthur Cox to defend itself.

Keane filed a High Court action in Dublin against the bookmaker on Monday, following a complaint from his solicitors that the billboard, on the day of the Republic of Ireland versus Scotland Euro qualifier, infringed his image rights.

Paddy Power, which has a track record of provocative advertising stunts, fixed the billboard on to the back of an articulated truck, which it parked near the Aviva Stadium on the day of the match.

Independence referendum

Keane was mocked up as the Scottish warrior, played in the film by

Mel Gibson

, with his face painted with an Irish Tricolour.

In a reference to Scotland’s rejection of independence in a referendum last year, the billboard said: “You may take our points but at least we have our freedom (ya wee pussies).”

Keane did not respond to a request for comment submitted through the Football Association of Ireland last night, while his UK-based agent, Michael Kennedy, declined to comment.

A spokesman for Paddy Power confirmed it was subject to a lawsuit over the matter: “It’s with the lawyers, so obviously we can’t talk about it, but hopefully they won’t take our freedom to have a bit of craic.”

Keane was last month cleared by a British court of an alleged public order offence over a row with a taxi driver.