ar utility error.

Hi, I am trying to create a library libMINE.a

I get the .o files using g++. Then I do the following command:

ar ruv libMINE.a a.o b.o c.o

This works very fine when I am logged in to the machine (remotely via 
ssh) where these files are. My uid=500. gid=500 on the remote machine.

However, when I do the same thing when this directory is mounted using 
sshfs as:

sshfs [email protected]:remote.dir ~/remote/ -o idmap=user -o 
allow_other -o uid=1000 -o gid=1000'

The ar complains with the following:
ar: unable to rename 'libMINE.a' reason: Operation not permitted

I check the ownership using ls -ln and I see it is 1000 1000.

So my question is how can I make it work? I am able to create files, 
delete files, edit files in this directory using sshfs w/o any issues.

thanks,
amit.