He was speaking on Friday at NBN Co's first-ever half-yearly presentation to media and analysts.
Under the NBN rollout plan introduced by the previous Labor Government, cherry-picking of central city sites was to have been clearly outlawed.
The NBN was predicated on a model whereby all regions of Australia would have similar pricing and access to the same basic down- and upload speeds. In effect the city networks would be subsidising the country and remote regions rollout.
TPG CEO David Teoh's plan to offer relatively low-cost fibre deployments to the basements of major city building, but ignore the regional and remote areas, would run counter to this.
"Any cherry-picking initiative by companies like TPG and others has the potential to undermine the economics of NBN Co," said Switkowski on Friday in a message clearly aimed at Comms Minister Malcolm Turnbull.
"The whole industry is looking for certainty in terms of the rules. Our position will be to explain to the committee, and therefore the Government what the consequences are of alternative market, or competition models."
Switkowski also announced plans for trials of the controversial fibre-to-the-node (FttN) technology in NSW and Victoria. The trials will be used to determine how NBN Co will deploy the technology, and be able to roll it out to a proposed 100,000 premises a month.
The FttN trials will be at Umina on the NSW Central Coast and Epping in Melbourne's northern suburbs. Up to 100 premises will be connected at each location.