A police operation has been launched in Cyprus in pursuit of a wooden box containing the ashes of a teenager that was snatched by thieves as his parents prepared to scatter their son’s remains.

The hunt for the missing vessel intensified on Saturday following a plea by the teenager’s distraught family. Kinga and Bartek Bebnarz had stopped at a restaurant near the beach where they had planned to spread the ashes when the incident occurred.

“In a totally brainless act robbers made off with the box after breaking into their rental car in a parking lot outside a taverna at Governor’s beach,” the Limassol police spokesman Yannis Sotiriadis said. “It means nothing to them and everything to the family. We are pulling out all the stops. We have expanded our investigations in the quest to retrieve it.”

The couple told the Guardian they would offer a €200 (£171) reward to anyone who could lead them to the ashes, stored in a small container embossed with the image of a dragonfly, the name of their son, Dennis who was 19, and the years of his birth and death.

The box containing the Ashes. Photograph: Handout

“This box symbolises our son and it means the world to us,” his mother, Kinga, said. “They took three bags but nothing else is precious, only this. We want to say to the robbers: ‘Please, please, return it.”

The family have driven up and down the island’s southern coast, pinning leaflets on trees and buildings and stopping at other seaside restaurants in an attempt to spread the word.

“Usually we take our son everywhere with us. It had been a long day and we had just stopped for a coffee and so had left all our stuff in the car before the ceremony with my parents and two other children,” Kinga said in the telephone interview. “When we came out and saw the smashed window and realised the car had been broken into and the bags had gone we all burst into tears. The box was in a black backpack and that had gone too.”

Although there had been no breakthough, they hope a car park camera could help trace the robbers.

The couple, Polish nationals who moved to Sweden in 2007 and set up a cleaning company, often travel, spending “beautiful moments” with their children abroad.

Five months after Dennis’s accidental death in Sweden they had decided to fly to Cyprus because it seemed a fitting place to end what had been an awful year, his mother said.

“The coast is so beautiful here and Dennis loved the sea. We all thought this would be a good way to end a terrible year for us. Our hope is that when the robbers realise what is inside one of the bags they will have human feelings and leave it somewhere for someone to find.”

The family had planned to be on the Mediterranean island for a week, returning to Sweden on Sunday . “We have to go because we have employees who need us there,” Kinga said. “But if anything changes, if anyone finds it, we will fly back immediately. We hope the thieves learn what has happened and do the right thing.”