The Canary Wharf-based European Medicines Agency said it is too early to know how Brexit will impact its operations.
It moved its headquarters to Canary Wharf in January 2015 and is the largest EU body in Britain, approving medicines for all EU countries.
It’s hundreds of staff occupy nine floors of the 20-storey skyscraper at 25, Churchill Place, which it signed a 25-year lease for with Canary Wharf Group .
A spokeswoman for the EMA said: “We respect the UK citizens’ decision to no longer be a part of the European Union.
“The people in the UK have taken their vote and it is now up to the UK government to decide how to act upon the outcome of the referendum.”
If Britain leaves the EU, the agency which employs 600 full-time staff, may have to find a new home and change the way it approves medicines, slowing the process.
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Its spokeswoman said Article 50 of the Treaty on the Functioning of the EU sets out the procedure to be followed in case a Member States notifies the European Council of its decision to withdraw from the Union.
She added: “No country has ever decided to leave the EU, so there is no precedent for this situation.
“It is too early to foresee the implications of this decision and we will be in close contact with the EU institutions. When we have concrete information, we will share it with our stakeholders.
“EMA will continue with its work with the goal to protect human and animal health and ensure access to medicines that are safe, effective and of good quality.”