Away from the on-the-ground search efforts, the administrator of a Facebook page set up to help find Mr Slater said somebody who was not the 19-year-old had logged in to his Instagram account.
People who had been “hacking” the social media accounts of his family were “sick in the head”, Rachel Louise Harg said.
She also said a fundraising page had been set up to help family and friends staying in Tenerife to search for him. Donations on the page have now exceeded £28,000.
Many members of the community in Oswaldtwistle have expressed concern about Mr Slater’s wellbeing.
The Reverend Matt Smith, from West End Methodist Church, said a service being held on Sunday would be “a chance for the community to come together”.
“It will be a normal service and we will offer our prayers for Jay and give an opportunity for people to leave messages for him and light candles,” he said.
Specialist officers are continuing to support Mr Slater’s family, Lancashire Police said on Saturday.
The force previously said it had offered to assist Spanish police searching for him, but were told their counterparts in Tenerife felt they had enough resources.
Mr Slater was on his first holiday without family and had travelled to attend the festival with two friends.
Lucy Law, thought to have been the last person to speak to him, said he told her in their call that he had missed a bus and decided to walk the 10-hour journey home but was lost, needed water and his phone was on 1% battery.
The Rural de Teno Park is about a 40-minute drive from where Mr Slater and his friends were staying.
A remote and wild national park, it is a world away from Los Cristianos and Playa de las Americas, the party town holiday resorts of the island’s south coast.
Deep ravines and huge daunting mountains make the national park a difficult place for the Spanish search teams to navigate.
