Only hours after Ukrainian officials were celebrating the EU taking the step of agreeing to open membership talks, Hungary put up strong opposition to the 50 billion euro aid package.
Hungarian President Viktor Orban says the decision is "senseless" and "irrational".
He had also opposed starting talks, but agreed to step out of the room to allow the other leaders take a consensus decision without him.
As well as Ukraine's accession to the bloc, they also yesterday voted to do the same for Moldova and granted Georgia candidate status.
The conflict in Gaza is expected to feature heavily during leaders' discussions. on the second day of the summit.
Taoiseach Leo Varadkar yesterday urged his colleagues to take a firmer stance on the war, and call for an end to the fighting between Israel and Hamas.
