Try this
ScriptManager.RegisterClientScriptBlock
ScriptManager.RegisterClientScriptBlock(this.up1, this.up1.GetType(), "page", "window.open('UserInfo.aspx?Status=A','_blank','toolbar=no,menubar=no,scrollbars=yes,height=500,width=650,left=200,top=10');", true);
Here up1 is updatepanel ID