Emergency services are investigating whether a miscommunication about a police code may have led to hiker Lily Hooper being incorrectly identified as alive.

Nearly 100 soldiers have joined the search for missing Sydney bushwalker Lily Hooper.

Lily Hooper was found on Thursday morning, more than a week after she went missing in dense bushland.

Lily Hooper had been missing in bush near Sydney for eight days.

Lily Hooper, 18, disappeared while hiking in Nattai National Park