The move has caused suppliers to question whether the revival of the TF is now a viable project.
A joint statement from Stadco and NAC, said: "Stadco and NAC confirm that for commercial reasons, production of bodyshells for the MG TF by Stadco will cease.
"Both parties are working to ensure minimum disruption to the workforce. Consultations with elected employee representatives will commence immediately and every effort will be made to assist those affected by this announcement. Stadco confirms that this will not have a material impact on its financial outlook."
The move places 30 jobs at risk.
Production of the MG TF had been expected to start by September, but the project has had several delays and there is still no indication of when production will start.
NAC MG has appointed 50 UK dealers, but they are all still waiting for cars and finalization on their contracts.
Quality issues with the Chinese-made components led NAC's September 2007 launch target to slip to February 2008. But after that date passed, Longbridge assembly plant executives would not tell AM whether they expect to have cars available at all this year.
John Lamb, spokesman for Birmingham Chamber of Commerce and Industry, told the Birmingham Post there would be concern among all suppliers about what was happening.
"If Stadco has made a decision on commercial grounds then that's perfectly understandable. However, we would be very disappointed if this element of production was lost to China," he said.