Gardaí have renewed their appeal for 18-year-old Cormac Clare, who has been missing from his home in Co Kildare for five days.
They would like to speak to anyone who may have seen Mr Clare near his home in Kilteel on Monday evening or hitch-hiking on the N7 or N81.
Superintendent Patrick Mangan said that they have carried out extensive searches since Monday.
"There are over 400 people, including local gardaí, garda divisional search teams, garda water unit, civil defence and members of the public from the locality, involved in the search."
Mr Clare is described as 6'1" and of thin build. He has short, tightly cut brown hair.
When last seen he was wearing a navy jacket, a wine coloured hooded top, plain navy cotton tracksuit bottoms and runners.
He may have been carrying a small black and green rucksack.