Bangkok: Rescuers located 12 boys and their soccer coach alive deep inside a partially flooded cave in northern Thailand late on Monday, more than a week after they went missing, bringing hope in a desperate search that has attracted international help and captivated the nation.

Chiang Rai Provincial Governor Narongsak Osatanakorn said the 13 were in the process of being rescued, but he cautioned that they were not out of peril yet.

"We found them safe. But the operation isn't over," he said in comments broadcast nationwide.

Rescue divers had spent much of Monday making preparations for a final push to locate the lost soccer players, aged 11 to 16, and their 25-year-old coach. They disappeared when flooding trapped them after entering the Tham Luang Nang Non cave on June 23.

Thai navy SEAL divers and rescue workers from other countries made initial progress through the narrow passageway early on Monday after passing through a key chamber on Sunday where high, murky waters had previously blocked their progress.