If Ukraine is judged to be ready, it can be granted candidate country status before accession negotiations can begin.
Ms von der Leyen indicated Ukraine was being given preferential treatment as she admitted this process is usually “a matter of years” but on this occasion was “I think a matter of weeks”.
Speaking at a joint press conference with Mr Zelensky, she said: “Dear Volodymyr, my message today is very clear. Ukraine belongs to the European family. We’ve heard your request loud and clear.
“And today we’re here to give you a first positive answer
“In this envelope, there is an important step towards EU membership. The questionnaire that is in here, is the basis for our discussion in the coming weeks. It is where your path towards Europe and the European Union begins.”
She added: “We stand ready 24 hours, 7 days a week, to support you in filling out this questionnaire. We know a lot about each other because we have been working intensively over the last few years.
“So it will not be, as usual, a matter of years, but weeks if we work closely together.”
The Ukrainian leader quipped: “Thank you so much. We’ll be ready with answers in one week.”
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He said: “Today I signed the application for Ukraine’s membership in the European Union. I’m sure it’s feasible.”
In a video address shortly after the invasion he also called for “immediate accession” to the EU.
He said: “We appeal to the European Union for Ukraine’s immediate accession under a new special procedure.
“We are grateful to our partners for supporting us, but our goal is to stand alongside all Europeans, and most importantly, stand on their level.
“I am confident that this is fair. I am confident that we deserve this. I am confident that all this is possible.”
A spokesperson for the European Commission told Business Insider in February membership had to be agreed by all existing EU member states.
“Applications are sent to the council, and the decision must be taken by unanimity by EU member states.”