Cannot authenticated using aws-cloud 2.6.0 and ES 1.6

I have recently upgraded a single node on my development environment from 1.4.4 to 1.6 and also upgraded the aws-cloud plugin. When I restart the sever i get the following messages in the log. They are the same credentials i used with the earlier version of the plugin. When i use the aws command line with the same credentials i am able to get the list of ec2 instances. The IAM User that i am using has full admin access so can't see how i would get an authentication or authorization failure?

Has anyone else come across this issue?

[2015-06-23 14:16:18,758][INFO ][discovery.ec2            ] [OzTAM Stsging Server] Exception while retrieving instance list from AWS API: AWS was not able to validate the provided access credentials (Service: AmazonEC2; Status Code: 401; Error Code: AuthFailure; Request ID: 0647bde8-8669-4886-882f-45302d79c737)
[2015-06-23 14:16:23,778][INFO ][discovery.ec2            ] [OzTAM Stsging Server] Exception while retrieving instance list from AWS API: AWS was not able to validate the provided access credentials (Service: AmazonEC2; Status Code: 401; Error Code: AuthFailure; Request ID: 462b9c2d-7711-43d2-8277-df049fc4191f)
[2015-06-23 14:16:28,793][INFO ][discovery.ec2            ] [OzTAM Stsging Server] Exception while retrieving instance list from AWS API: AWS was not able to validate the provided access credentials (Service: AmazonEC2; Status Code: 401; Error Code: AuthFailure; Request ID: a580c7ea-a243-4750-bbd4-07294476fdfe)
[2015-06-23 14:16:28,804][INFO ][cluster.service          ] [OzTAM Stsging Server] new_master [OzTAM Stsging Server][bp2lvAI9Tiq5mSztJTcYpg][oztam-avmh-dev-01][inet[/172.31.7.102:9300]]{aws_availability_zone=ap-southeast-2b, master=true}, reason: zen-disco-join (elected_as_master)