Mr Twomey hasn’t been seen since early Sunday morning and his distraught partner has said it is “very out of character”
The 31 year old’s phone was found in a farmyard five miles from his home in Co Cork.
Ciara Byrne, Mr Twomey’s partner said the father of two disappeared after his nephew’s birthday party in Fairhill, Co Cork.
A taxi was hailed by Mr Twomey and his partner at 3am but Diarmuid Twomey didn’t take the taxi as he didn’t feel well.
Fields in the Cork area of Whitechurch, Carrignavar and Ballinhina are being searched by specialist dog teams, civil defence and a coast guard helicopter.
Worried family and friends have beenn scouring the area also.
He is described as being 6ft tall, stocky build. He has dark brown hair, on his last sighting he was wearing a blue check shirt, beige chinos and brown runners.
Anyone who information or a sighting of Mr Twomey, appealing to taxi drivers who may have seen the young man are asked to contact them at Gurranabraher Garda statioon on 021 4946200.