A man accused of murdering his long-term partner has told his trial he is not a violent person, and never intended to hurt him.

Desmond Duffy denies intentionally strangling Desmond O'Sullivan to death at their home in Somerville in Rathmines in Dublin in May 2016.

Mr Duffy and Mr O'Sullivan were together for over 30 years and were referred to as 'Big Des' and 'Little Des' by those who knew them.

Mr Duffy told the jury he was regularly abused by his partner, and claims he acted in self-defence on the night in question.

From the stand on Thursday, he said Mr O'Sullivan started punching him when they returned to their home after spending a day drinking in May 2016.

He said he went to bed in the hope of diffusing the situation, but was followed upstairs where the physical assault continued.

He said he remembered shouting 'This has to stop. Please leave me alone. You can't keep doing this to me' before going back downstairs.

He told the court he put his hand on his neck and began pushed him up against a wall to get him away from him when suddenly he just slid down the wall and rolled on to his side.

He said he went into deep shock when he realised he was dead and was devastated and heartbroken by what happened.