Suppliers who have rejected traffic light labelling because of fears it will “demonise ” their products are expected to come under increased pressure to compromise, following Tesco’s decision to adopt traffic lights after years of opposition.

Tesco’s decision was described as a “pivotal moment”, as Morrisons, the one leading supermarket yet to back traffic lights, indicated it might also move into line.

Ministers have applied huge pressure on retailers to back traffic lights in response to Health NGOs’ demands. They are now confident that supermarket chiefs will agree on a universal system, involving a combination of traffic lights and GDAs, which could be used as new pledge under the Responsibility Deal.

The Grocer exclusively revealed in May that the DH was re-igniting calls for traffic lights. At the time, sources said they expected opposition from retailers - but now it is branded suppliers that are the stumbling block.

This week, health secretary Andrew Lansley said he would be “pushing hard” for manufacturers to drop their opposition.

“Tesco’s decision is a game changer,” said a source involved in the consultation. “We now have the overwhelming number of retailers agreeing to traffic lights.”

A spokeswoman for Morrisons told The Grocer the supermarket was “open minded”.

“We believe greater consistency between retailers and manufacturers is in the consumer interest, but issues need to be addressed to achieve this,” she said.