Jan Woerner made his remarks against a backdrop of increasingly bitter wrangling over the UK’s future involvement in the project, which is a rival to the US-owned global positioning service.
Last week EU Brexit negotiator Michel Barnier conceded: “There is a way for the UK to be included in a partnership about Galileo as a user of (services) including the PRS.”
However, he remains steadfast in his position that Britain could have no involvement in Galileo’s future development, adding: “The facts have consequences.”
Speaking to Andrew Marr at the weekend, Prime Minister Theresa May claimed the EU had been taking Britain “for a ride”.
She added: “The UK has been contributing significantly to the Galileo programme so far.
“We are still discussing that with them.
“What we as a Government have said is that if that is your decision we will ensure that Britain has what Britain needs, and we will do it ourselves.”
In a blog published earlier this month, Dr Woerner has expressed disquiet after the EU unveiled plans to rename the European Global Navigation System Agency in Prague the EU Agency for the Space Programme.
And while he said his concerns over possible duplication of services had been eased by discussions with European Commission officials, question marks over the future of Galileo remained.
He told Express.co.uk: “The concern going forward is Brexit.
“The UK and the EU are trying to solve these issues but at the moment we just cannot say what the outcome will be.
“It is important that there is a third-party agreement which would allow British involvement.
“Unfortunately I am not able to decide about that – I wish I could do.
“There needs to be an agreement in order to have the UK on board with all the EU space activities.”
The ESA is an independent body which has close links to countries outside the continent of Europe, including Canada, and Britain is in fact one of the initial signatories, helping draft its charter in 1980.
Dr Woerner stressed that irrespective of what happens with Galileo, the UK will remain a member of the ESA,
He explained: “Britain remains a strong and stable partner.”