"I do not think that the first of July is feasible," Austrian Interior Minister Wolfgang Sobotka said as he arrived for a meeting with his EU counterparts in Luxembourg.
"We really need to have a legally flawless solution. If not, Austria cannot agree," said Sobotka, whose country took in record numbers of refugees last year, mostly from war-torn Syria.
The European Union agreed in March to offer Turkey visa free access by July 1, increased aid and speeded up accession talks in return for Ankara controlling the flood of migrants crossing into Greece.
Protests were held against Erdogan in Vienna during Turkish elections. Photo: Paul Gillingwater
But Ankara warned late last month it would drop the whole agreement if there was no visa deal after the European Commission laid down a series of conditions, including changes to Turkey's catch-all anti-terrorism laws so as to meet EU concerns over human rights.
Dutch Interior Minister Klass Dijkhoff said separately the EU was working closely with Turkey on the issue but "it is not a negotiation process".
"If Turkey wants visa liberalisation, they know the requirements they should meet," said Dijkhoff, whose country currently holds the EU's six-month presidency.
"There is a date that is the first of July; if they meet it, then we can go on; if they don't, then we have to see when they can meet criteria," he added.
Turkish President Recep Tayyip Erdogan has said he could wait until October to get the visa deal but he has also warned the EU against pushing Ankara too far, insisting that its anti-terror laws are fully justified.