John Aherne came to Sweden to celebrate St. Patrick’s weekend with his close friend Karl Lambert.
“I’ve called everybody I can think of: police, hospitals and the Irish Embassy. But I’m drawing blanks,” said Lambert.
The two men went out with friends on Saturday night and had a few drinks together at a city centre pub.
When Aherne decided he was ready to go home, Lambert stayed behind and gave his friend a set of spare keys.
“He stopped off at a restaurant on the ground floor of the apartment building,” said Lambert, who has spoken to staff at the Orion restaurant on Katarina Bangata in the south of the city.
Aherne had a drink at the restaurant. Leaving his coat on a chair and his phone on the bar, he went outside. He has not been seen since.
“He told a guy in the bar he was just going out for a smoke and would be back in a minute,” said Lambert.
Police in Stockholm said they were looking into the matter.
“He’s still missing. We have issued a description of him and we’ve been in touch with his family,” said police spokeswoman Jackie Moberg.
Aherne, who is an accountant, was due to leave Sweden on Monday morning but his passport is still at his friend’s apartment.
“His bank card hasn’t been used since Saturday night,” said Lambert.
Members of Aherne’s family said they were considering coming to Sweden on Tuesday in order to be closer to the investigation.
The family have also been in contact with Aherne’s girlfriend, who is currently in San Francisco.
John Aherne is described by his family as being around 1.77m (5’10”) tall, weighing 79 kilos (12.5 stone), with black hair and brown eyes.
He was wearing blue jeans and a blue and white striped shirt under a light yellow wool jumper at the time of his disappearance.
Anyone with information relevant to the case is advised to call the police at 114 14.