function ajax_block_user(username, callback) {
    jQuery.ajax({
        type: "GET",
        url: '/user/block/' + username,
        cache: false,
        data: {
            'ajax': 1
        },
        dataType: 'text',
        success: function(data, textStatus, xhr) { 
            switch(data) {
                case 'NOT_LOGINNED':
                    window.location = '/login';
                    break;

                case 'OK':
                    if(callback) callback();
                    break;
            }
     },
        error: function(xhr) { alert(ZORPIA_JS_LANG.ENCOUTER_SOME_ERROR); }
    });

}