Many other workers have isolated themselves, but the exact figures remain uncertain.
It was understood after one person was first confirmed positive last week, 15 other staff were asked to self-isolate.
As of Thursday, confirmed cases had risen to four and today that number had risen to 11.
Dr Steve Iley, Chief Medical Officer of JLR, said: “The health, safety and well-being of the Jaguar Land Rover family is our primary concern.
“We have developed a robust protocol and guidelines to ensure that effective social distancing, hygiene and health measures are in place at all of our sites and are secured by Covid.
“A small number of employees based at our manufacturing plant in Solihull have tested positive for Covid 19 and are self-isolating.
“Through contact tracing and working in conjunction with Public Health England, we have identified anyone who has been in close contact with these people at work and they are also self-isolating. ”
The company said last week that other employees who may have come into contact with the first confirmed cases were isolating themselves.
A source said of the latest figures: “One worker tested positive first and then everyone he worked with was sent home to self-isolate.
“Everyone who has tested positive is believed to be between 18 and 40 years old. ”
When production started at the factory after the lockdown, strict measures were put in place to protect workers’ health.
These included temperature controls, two-meter distance markers, face shields in sections where this is not possible, the introduction of one-way systems in factories, improved cleaning regimes and hand sanitizers.
The source said: “To give them their due, the company has implemented many measures, there are even numbered sinks that correspond to numbered toilets for use.
“There are a lot of masks and hand gel. If people are working together, they have to wear masks. ”
A spokesperson for JLR previously said: “A thorough review of all production lines, technical facilities, offices and common areas has been undertaken.
“This is about creating a strong protocol and guidelines to ensure that effective social distancing, hygiene and health measures are in place as the company gradually returns to manufacturing.
“The health and well-being of employees are at the center of this plan and, with the implementation of the new protocol, employees will experience a significant number of changes in their working day as soon as they enter the site.
“We continue to monitor the COVID-19 situation and follow the advice of all relevant authorities in the markets in which we operate. “