Greek emergency forces have expanded the search for a British man who went missing on Sunday as he hiked in the Pindus mountain range close to the Albanian border.

Police, who identified the Briton as Robert Frome, 26, said two helicopters and two specially trained dogs were participating in the operation, one of the biggest of its kind in north-west Greece. On Wednesday volunteers with intimate knowledge of the rocky terrain were also looking for the Briton, who was travelling alone.

“We have broadened the search in what is a very mountainous area,” said Emelia Goulas, a police spokeswoman in Ioannina, the capital of the Epirus region. “Specialised fire brigade units backed up by dogs and, as of this morning, two helicopters are all out there. In intensity and breadth I cannot remember an operation like this,” she said.

Frome, who had flown into northern Greece on a trekking holiday, was last seen in Konitsa, a mountain town in the picturesque region where he was renting a room. With its spectacular stone villages, known as the Zagorohoria, as well as forests, gorges and fast-flowing rivers, the area is especially popular with hikers and climbers.

Greek authorities were alerted by Frome’s father, who raised the alarm when the tourist failed to answer his phone. “We launched the rescue operation at 5pm on Sunday as soon as they got in touch. By Monday we had found his rental car near the village of Mikro Papingo. It was parked and locked, suggesting that he had decided to walk in that area,” Goulas said. “Our fear is that he may have slipped and fallen, which is not uncommon.”

Rescue workers were focused on an area around Astraka, one of the peaks of Mount Tymfi. The Briton’s mobile had been deactivated, making the search harder still. “If it was on we’d have satellite support to help pinpoint his location,” a police spokeswoman in Athens added.

This is not the first time this summer a missing British holidaymaker has been the focus of a police hunt in Greece. Last month, a massive operation was launched on the Aegean island of Ikaria when a British astrophysicist, Natalie Christopher, failed to return from a morning jog. The 35-year-old extreme sports enthusiast was eventually found in a ravine, her lifeless body crushed by a boulder.

“We won’t stop looking until we find him, but every day that passes the window of hope narrows,” Goulas said.