Several EU leaders have already stressed that a decision on warplanes would be a collective move.
Some are keen to avoid having the debate being played out in public, while there is also concern about escalation and playing into Russian narratives.
The Kremlin warned on Thursday that the line between direct and indirect Western involvement in the conflict was disappearing.
Mr Zelensky said that certain agreements had been made that were positive but not yet public, and presidential office adviser Mykhaylo Podolyak later told Ukrainian TV that long-range missiles and attack aircraft would be supplied this year, although it was up to negotiations. sagame