Spring Integration SFTP inbound adapter unable to copy files - file

Question

I have a SFTP inbound channel set up to poll a remote sftp server and copy files to a local directory. When it runs, it gives me a 'Permission denied' error, but in the log file it correctly mentions the file name. So it appears to be able to correctly list the contents of the remote path, but is unable to read the files.
I haven't been able to figure out what the access issue is exactly. When i fiddled with it on a test server i could see I would get the same issue if the sftp user had at least r-x access on the remote dir, but no access on the files themselves. However on the live server where i get the issue, the user does have this required level of access.
Running the sftp command copies the files without any issues:
/usr/bin/sftp -2 -i KEYFILE USER#SERVER:REMOTEDIR/FILEPATTERN* LOCALDIR
Here is how i have the SFTP channel in my Spring Integration config:
<int:poller default="true" fixed-rate="${fixed.rate}" />
<bean id="sftpClientFactory"
class="org.springframework.integration.sftp.session.DefaultSftpSessionFactory">
<property name="host" value="${sftp.inbound.channel.host}" />
<property name="port" value="${sftp.inbound.channel.availableServerPort}" />
<property name="user" value="${sftp.inbound.channel.userid}" />
<property name="password" value="${sftp.inbound.channel.password}" />
<property name="privateKey" value="file:///${sftp.inbound.channel.server.key}"></property>
</bean>
<int-sftp:inbound-channel-adapter id="sftpInbound"
channel="sftpChannel" session-factory="sftpClientFactory"
filename-pattern="${input.file.format}" auto-create-local-directory="true"
delete-remote-files="false" remote-directory="${sftp.inbound.channel.remote.directory}"
local-directory="${sftp.inbound.channel.local.directory}">
</int-sftp:inbound-channel-adapter>
<int:channel id="sftpChannel">
<int:queue />
</int:channel>
The project is using Spring Integration version 4.0.4-RELEASE
This is the full exception trace. The file name gets correctly logged at the placeholder <FILENAME>
ERROR 9860 --- [ask-scheduler-2] o.s.integration.handler.LoggingHandler : org.springframework.messaging.MessagingException: Problem occurred while synchronizing remote to local directory
at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer.synchronizeToLocalDirectory(AbstractInboundFileSynchronizer.java:209)
at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizingMessageSource.receive(AbstractInboundFileSynchronizingMessageSource.java:167)
at org.springframework.integration.endpoint.SourcePollingChannelAdapter.receiveMessage(SourcePollingChannelAdapter.java:124)
at org.springframework.integration.endpoint.AbstractPollingEndpoint.doPoll(AbstractPollingEndpoint.java:192)
at org.springframework.integration.endpoint.AbstractPollingEndpoint.access$000(AbstractPollingEndpoint.java:55)
at org.springframework.integration.endpoint.AbstractPollingEndpoint$1.call(AbstractPollingEndpoint.java:149)
at org.springframework.integration.endpoint.AbstractPollingEndpoint$1.call(AbstractPollingEndpoint.java:146)
at org.springframework.integration.endpoint.AbstractPollingEndpoint$Poller$1.run(AbstractPollingEndpoint.java:298)
at org.springframework.integration.util.ErrorHandlingTaskExecutor$1.run(ErrorHandlingTaskExecutor.java:52)
at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:50)
at org.springframework.integration.util.ErrorHandlingTaskExecutor.execute(ErrorHandlingTaskExecutor.java:49)
at org.springframework.integration.endpoint.AbstractPollingEndpoint$Poller.run(AbstractPollingEndpoint.java:292)
at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)
at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:81)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:178)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:292)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)
Caused by: org.springframework.messaging.MessagingException: Failure occurred while copying from remote to local directory
at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer.copyFileToLocalDirectory(AbstractInboundFileSynchronizer.java:238)
at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer$1.doInSession(AbstractInboundFileSynchronizer.java:177)
at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer$1.doInSession(AbstractInboundFileSynchronizer.java:167)
at org.springframework.integration.file.remote.RemoteFileTemplate.execute(RemoteFileTemplate.java:302)
at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer.synchronizeToLocalDirectory(AbstractInboundFileSynchronizer.java:167)
... 20 more
Caused by: org.springframework.core.NestedIOException: failed to read file <FILENAME>; nested exception is 3: Permission denied
at org.springframework.integration.sftp.session.SftpSession.read(SftpSession.java:132)
at org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer.copyFileToLocalDirectory(AbstractInboundFileSynchronizer.java:231)
... 24 more
Caused by: 3: Permission denied
at com.jcraft.jsch.ChannelSftp.throwStatusError(ChannelSftp.java:2846)
at com.jcraft.jsch.ChannelSftp.get(ChannelSftp.java:1313)
at com.jcraft.jsch.ChannelSftp.get(ChannelSftp.java:1266)
at org.springframework.integration.sftp.session.SftpSession.read(SftpSession.java:128)
... 25 more
I'll appreciate if anyone can help me figure out what I may be missing.