Limits to passing parameters to reportserver via HTTP post?

Hi all,

I'm passing params to my reportserver from a web page using HTTP POST. However, there is a multi value parameter that I want to send a lot of data to (usually over 100 items). When the data is passed to the report I get a 'page could not be displayed' message and it looks like the parameters are being placed into the querystring when they hit the server - does this mean my post request is being translated to a get request by SRS which is then passed to the reportsever url?

It works fine with less parameters

Anyone know if there is any way round this?

Thanks,

Charles