diff --git a/src/xcp_ng_dev/cli.py b/src/xcp_ng_dev/cli.py
index 642d543..2765d27 100755
--- a/src/xcp_ng_dev/cli.py
+++ b/src/xcp_ng_dev/cli.py
@@ -54,6 +54,7 @@ def add_common_args(parser):
     group.add_argument('--disablerepo',
                        help='disable repositories. Same syntax as yum\'s --disablerepo parameter. '
                        'If both --enablerepo and --disablerepo are set, --disablerepo will be applied first')
+    group.add_argument('-U', '--disable-upstream-repos', action='store_true', help='disable the upstream repositories')
     group.add_argument('--no-update', action='store_true',
                        help='do not run "yum update" on container start, use it as it was at build time')
 
@@ -170,6 +171,8 @@ def container(args):
     if args.env:
         for env in args.env:
             docker_args += ["-e", env]
+    if args.disable_upstream_repos:
+        docker_args += ["-e", "DISABLE_UPSTREAM_REPOS=true"]
     if args.enablerepo:
         docker_args += ["-e", "ENABLEREPO=%s" % args.enablerepo]
     if args.disablerepo:
diff --git a/src/xcp_ng_dev/files/Dockerfile-8.x b/src/xcp_ng_dev/files/Dockerfile-8.x
index b6e404c..c9dcc2e 100644
--- a/src/xcp_ng_dev/files/Dockerfile-8.x
+++ b/src/xcp_ng_dev/files/Dockerfile-8.x
@@ -10,6 +10,8 @@ ARG     CENTOS_VERSION
 COPY    files/CentOS-Vault.repo.in /etc/yum.repos.d/CentOS-Vault-7.5.repo
 RUN     sed -i -e "s/@CENTOS_VERSION@/${CENTOS_VERSION}/g" /etc/yum.repos.d/CentOS-Vault-7.5.repo
 
+ENV     UPSTREAM_REPOS="C${CENTOS_VERSION}-base C${CENTOS_VERSION}-updates C${CENTOS_VERSION}-extras"
+
 # Add our repositories
 # Repository file depends on the target version of XCP-ng, and is pre-processed by build.sh
 ARG     XCP_NG_BRANCH=8.3
diff --git a/src/xcp_ng_dev/files/Dockerfile-9.x b/src/xcp_ng_dev/files/Dockerfile-9.x
index be318d0..b1bb75d 100644
--- a/src/xcp_ng_dev/files/Dockerfile-9.x
+++ b/src/xcp_ng_dev/files/Dockerfile-9.x
@@ -41,6 +41,8 @@ RUN     dnf update -y \
         # clean package cache to avoid download errors
         && yum clean all
 
+ENV     UPSTREAM_REPOS="appstream baseos crb epel extras alma10-devel"
+
 # enable repositories commonly required to build
 RUN     dnf config-manager --enable crb
 
diff --git a/src/xcp_ng_dev/files/init-container.sh b/src/xcp_ng_dev/files/init-container.sh
index 27f8ef0..3637dcc 100755
--- a/src/xcp_ng_dev/files/init-container.sh
+++ b/src/xcp_ng_dev/files/init-container.sh
@@ -46,6 +46,13 @@ case "$OS_RELEASE" in
     *) echo >&2 "ERROR: unknown release, cannot know package manager"; exit 1 ;;
 esac
 
+# disable upstream repositories if needed
+if [ "$DISABLE_UPSTREAM_REPOS" == "true" ]; then
+    for repo in $UPSTREAM_REPOS; do
+        sudo $CFGMGR --disable "$repo"
+    done
+fi
+
 # disable repositories if needed
 if [ -n "$DISABLEREPO" ]; then
     sudo $CFGMGR --disable "$DISABLEREPO"