Federal agencies have joined the search for Julian Sands, using mobile phone forensics to help pinpoint the location of the British actor, local police have said.

Both national and state officials are now working with the San Bernardino County Sheriff’s office, one week on after the actor was first reported missing in the southern Californian mountains.

As of Friday, ground crews were still unable to continue their search efforts, due to the risk of avalanches in the area, and authorities said there was still “no time set” for when they would begin.

The involvement of federal and state agencies marks a step up in the search for Sands.

The county sheriff’s department previously revealed that pings from the actor’s phone appeared to show he had been on the move heading further into the mountainous area of Baldy Bowl on the day he was reported missing – January 13.

“We are working with state and federal agencies that have cell phone forensics to assist us in pinpointing a location, but so far no new info has been developed,” a spokesperson from the department told the PA news agency.

The department previously told PA there was still “no hard deadline” and “no date set” for calling off efforts – and the incident is still being classified as a search and rescue operation.

On Thursday, Sands’ family towed his car from a car park where it was discovered during the search.

Mount Baldy residents noted the “extreme” conditions but said they would not “rule anything out” in the mission to find Sands.