A reservoir in west Dublin is being searched as part of the investigation into the disappearance of Thomas Kennedy (81).

The man from Finglas was last seen three weeks ago putting his bins outside his home in the Virginia Park area.

Gardaí and his family launched a massive search operation, but have so far been unable to trace the pensioner.

The scouring of a reservoir near Dunsink Lane follows a trawl of the Royal Canal and Tolka River.

The son of the pensioner previously told Newstalk that his father had not accessed his bank account since he went missing.

Several sightings have been reported of the him - but so far nothing has been found.

Mr Kennedy is described as being 5-foot-4 in height, of slim build with short grey hair.

He was wearing a black rain jacket with a hood, short sleeved white and blue polo shirt, dark chino style trousers, black shoes with a Velcro fastener and no laces.

Mr Kennedy also wears glasses and a watch.

Anyone with any information on his whereabouts is asked to contact Finglas garda station on 01-6667500, the Garda Confidential Line at 1800-666-111 or any garda station.