Britain will stay in the European Space Agency when it leaves the EU, but will have to renegotiate terms to continue participating in certain projects, the ESA said Wednesday.

The ESA is autonomous from the European Union and should not be directly affected by the "Brexit", Jean Bruston, head of the agency's EU policy office, told journalists in Paris.

Twenty EU countries -- including Britain -- belong to ESA, which gets about a quarter of its budget from the currently 28-member bloc.

The other two members are non-EU countries Norway and Switzerland.

Apart from its ESA participation, Britain is also party to several EU-driven space programmes.

These include the Copernicus satellite system to monitor environmental damage and boost disaster relief, and Horizon 2020, which seeks to boost scientific research and innovation.

"As soon as it (Britain) is leaving the EU it is not participating in these programmes any longer," said Bruston.

Furthermore, UK-based companies hold contracts worth tens of millions of euros from ESA to supply hardware for Copernicus as well as the Galileo satnav system, a rival to America's GPS.

"If nothing changes (and Brexit goes ahead), we would have to stop these contracts," said Bruston.

Britain could still contribute to Galileo and Copernicus if it negotiated a third-party agreement with the EU, which is what Norway and Switzerland have done.

As non-EU members, they make project-specific contributions to the EU. The ESA, in turn, can place contracts with companies in those countries.

Tweaks would have to be made in the existing EU-ESA agreement for the UK to follow suit, said Bruston.

Britain voted 52 percent to 48 percent in a referendum in June to leave the 28-member European Union, but has yet to invoke an article of the EU's Lisbon Treaty for the split to take effect.

ESA director-general Jan Woerner told AFP this week "the UK will remain a member state of ESA, this is very clear".

"But of course, as we are also dealing with European programmes like Copernicus and Galileo, and also the question of UK citizens working on the continent and all these legal issues, we have to take it into account."