BRUSSELS, March 28 (Xinhua) -- The European Commission plans to exclude Britain from its Galileo satellite program after Brexit due to security concerns, British media reported Tuesday.

In a letter from the commission to the British government, the EU said British businesses may no longer be able to bid on the Galileo project, and the British military might also not be able to use the system, according to online tech publisher The Register.

Galileo aims to build a European rival to the American GPS system, or possibly, Russia's Global Navigation Satellite System -- also known as GLONASS -- by Russia.

European Commission spokesman Alexander Winterstein said it was "the right time to start thinking about adjusting co-operation" on Galileo, as Britain will no longer be a part of the EU on March 29, 2019.

British Defence Secretary Gavin Williamson said the commission's approach was "deeply disappointing".

He said the decision "not only will be detrimental to Britain but will also be highly detrimental to European security".

British Prime Minister Theresa May has said she wants a full defense and security treaty with the EU, but negotiations are far from complete.

Britain has contributed expertise as well as fund to Galileo. It is also preparing for a rift with the EU with plans to launch its own spaceport, British media reported.