Thanks for your response .Kindly find the below comments
-> Can you check user has sudo/root permissions on these hosts? --> Sudo is working fine and permissions looks ok
-> Can you do agent hard restart on these hosts and try? --> Rebooted the box
-> recheck private key is valid and correct one. --> Yes, able to do login using the key from OS level (between the hosts)
But still the issue persists .Kindly advice