Rescuers in Laos say they are investigating a possible “knocking response” deep inside a flooded cave network where two men are believed to remain trapped.

Hungry and weak, the Laos cave survivors huddled together in damp darkness for 11 days, clinging to hope as a wall of water blocked their way out.

Rescuers in Laos say they are investigating a possible “knocking response” deep inside a flooded cave network where two men are believed to remain trapped.