In a private briefing for city analysts, the retail giant said it believed there was potential to build 1,000 new stores.
A Tesco spokesman said: "There is room for more Express stores in sites where there is consumer demand, but we haven't set a target."
The briefing echoes a similar statement made by the company in 2005, when it had 600 Express stores and argued that another 600 would be "sustainable".
Commenting on the leak, Ken Parsons, chief executive of the Rural Shops Alliance, said: "We have reached the point in the UK where it is wrong for one company to control yet more of the grocery market. Tesco's announcement on its expansion plans should be a wake-up call for government to say clearly just how much of the grocery market it is prepared to let one company control."
James Lowman of the Association of Convenience Stores added: "It is clearly a threat, but local shops are getting to know what to expect from Tesco Express."