Six days after Jay Slater went missing in Tenerife, his mother has stated that she thinks Spanish police have stepped up their hunt for her son. Slater is 19 years old.

Dogs were called in to aid in the search on Saturday afternoon while police, firefighters, and search and rescue personnel combed through a substantial portion of the valley where Slater was last seen.

Debbie Duncan told the Guardian that she spent eight hours on Friday in a police station listening to the cops lay out their meticulous plans for finding the missing Lancashire apprentice bricklayer. She stated, "I think it's been stepped up," calling it "too right."

Duncan, who flew to the island on Tuesday, a day after Slater went missing, said she still believes “something untoward” may have happened to her son, and that police had told her they were “investigating all leads”.

On Saturday, police were at the holiday home that Slater had visited before he disappeared, standing guard outside while tourists ate at the adjoining cafe.

Police were also seen near a house further down the valley, close to the palm tree where Slater’s phone last “pinged”, and which is believed to be his last known location.

Later on Saturday, Jay’s father Warren Slater, 58, visited the scene in the village of Masca where his son went missing.

He was joined by Jay’s brother Zak, 24, and told reporters he just wanted “the boy back”.

Warren is estranged from Jay’s mother, who did not feel ready to join them.

On Friday, rescuers said they were focusing on an area 30km square, concentrating on the paths of the valley surrounding the rural village of Masca, as well as two ravines.

With Slater now missing for almost a week, rumours and conspiracy theories about his disappearance continue to spread online, with social media “sleuths” speculating on social media platforms, including TikTok and Facebook.

The administrator of an official Facebook page set up to help find him, Rach Louise Harg, said in a post on the page that somebody had logged into Slater’s Instagram account who was not him.

Duncan also said Spanish police were concerned that “noise” around the case may have a negative impact on the search.

“They have actually said that there’s too much noise, that’s affecting it,” she said. “They’ve got all the plans, their locations. They have got this map they were showing us, shaded different colours.”

Duncan renewed calls from the family for British police to fly to Tenerife to join the search. But last night, in a statement, Lancashire constabulary said that their offer of help had been refused by Spanish counterparts.

“We’ve had a problem with the language barrier,” Duncan said. “It’s difficult with all the Spanish police and British police, they have to let the Spanish police do the investigation, but I want somebody to come out here.”

Lancashire police said specialist officers from the force were continuing to support the family.

“While this case falls outside the jurisdiction of UK policing, we have made an offer of support to the Guardia Civil to see if they need any additional resources,” a spokesperson said.

“They have confirmed that at this time they are satisfied that they have the resources they need, but that offer remains open and they will contact us should that position change.”

On Friday, search teams in the Rural De Teno nature park said they had not given up hope of finding Slater alive. They said the search focused on three distinct areas, covering a distance of 30sq km.

“We still have hope that he’s alive, up until the last moment when the last hope is lost,” one rescuer said. “The truth is that we feel a bit frustrated because we can’t find him. It’s so big [here] that it’s very difficult to search in such a steep area. But we’re doing everything we can.

“We haven’t found anything, we have combed this entire trail, we’ve been up and down but, until now, nothing.”

The teenager was last heard from on Monday morning when he phoned a friend saying he was lost, needed water, and that his phone battery was on 1%.

He had been with friends at the NRG music festival, but had gone back with two men he had met, who are believed to be British, to their holiday cottage on the outskirts of the village of Masca, almost 25 miles (40km) north of the holiday resort in Los Cristianos where he was staying with friends.

A spokesperson for the music festival said it had been able to “give some practical support” to Slater’s family.

“That such a devastating situation has arisen has deeply affected us all,” they said, adding that they had been “inspired by [the family’s] resilience and determination”.

The last known sighting of Slater was by Ofelia Medina Hernandez, whose brother owns the cottage where the men were staying.

She said Slater had asked her about bus times, then later saw him walking up a hill – in the opposite direction to Los Cristianos.

“He walked along the road when I saw him for the last time, up there … He was there alone,” she said. “He was walking normally, though fast, a little fast.”

To walk back on foot would have taken about 11 hours.

On Friday evening, search teams deployed dogs and drones from the Cruz de Hilda viewpoint, near where Slater was last seen.

The Guardia Civil said on Friday: “There is a search on going and the police operation is focused on the area of Masca (Tenerife). We cannot confirm any more information.”