We're trying to do an automated network installation using pxe.

We installed netboot tools (14.04 LTS) and extracted the ubuntu-14.04-desktop-amd64.iso contents into http server.
We saw that we have to download missing repository main/debian-installer (about 50MB) which is necessary for netboot installation, but it is not included within the iso distribution file.

Installation process begin, and failed during "Download installer components" phase saying the installer failed to download a file from the mirror.
The question is "Is it possible to add main/debian-installer repository to the original ubuntu-14.04-desktop-amd64.iso contents and how ?". We want to do automatic installation without Internet access.