Pip install fails to find the build-system.requires package

I have a docker image with poetry-core installed and inside the container I tried to run a pip install of project and it failed with the package not found error

r

oot@test-86978fffbb-6rx79:/home# /usr/local/bin/python3 -m pip show poetry-core
Name: poetry-core
Version: 1.0.8
Summary: Poetry PEP 517 Build Backend
Home-page: https://github.com/python-poetry/poetry-core
Author: Sébastien Eustace
Author-email: sebastien@eustace.io
License: MIT
Location: /usr/local/lib/python3.9/site-packages
Requires: 
Required-by:

My pyproject.toml

[build-system]
requires = ["poetry-core>=1.0.0"]
build-backend = "poetry.core.masonry.api" 

When I run pip install with internet disabled, it fails not able to find the poetry-core

root@test-86978fffbb-6rx79:/app# /usr/local/bin/python3 -m pip install /app/
Processing /app
  Installing build dependencies ... error
  error: subprocess-exited-with-error
  
  × pip subprocess to install build dependencies did not run successfully.
  ? exit code: 1
  ??> [2 lines of output]
      ERROR: Could not find a version that satisfies the requirement poetry-core>=1.0.0 (from versions: none)
      ERROR: No matching distribution found for poetry-core>=1.0.0
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: subprocess-exited-with-error

× pip subprocess to install build dependencies did not run successfully.
? exit code: 1
??> See above for output.