Police searching for actress Naya Rivera have confirmed that she has not yet been found almost 24 hours after her disappearance from a Californian lake.

The 33-year-old Glee star rented a boat and ventured out on to Lake Piru with her four-year-old son Josey Hollis Dorsey on Wednesday afternoon, but just three hours later the boat was found adrift with the child asleep alone on board.

Josey is said to have told police that his mother jumped into the water but did not resurface, prompting an immediate search of the lake and its immediate environs.

Earlier on Thursday it was reported that the search operation had been reclassified from a rescue mission to a recovery mission, with officers working on the assumption that Rivera has drowned.

In a fresh update issued at 2pm local time (10pm UK), Ventura County Sheriff's office said: "The search continues for Naya Rivera at Lake Piru, but she has not yet been found. There will be a media briefing to provide an operational update at 3 pm today at Lake Piru."

More than 80 people are now involved in locating Rivera, with specialised diving and rescue teams being drafted in from across Los Angeles to assist in the effort.