Turkey's president has told the EU it will not change its anti-terror laws in return for visa-free travel.
"We'll go our way, you go yours," Recep Tayyip Erdogan said.
The EU says Turkey needs to narrow its definition of terrorism to qualify for visa-free travel - which is part of a larger deal between the sides aimed at easing Europe's migration crisis.
Mr Erdogan was speaking a day after PM Ahmet Davutoglu, who largely negotiated the EU deal, said he was stepping down.
Mr Davutoglu had also reportedly opposed Mr Erdogan's plan to give more power to the presidency. Mr Erdogan said the proposed constitutional changes were a national need, not a personal requirement.
The wide-ranging EU-Turkey deal involves the return of migrants, mainly Syrians, from Greece to Turkey, along with increased aid and other measures.
One of these is to allow Turkish citizens visa-free travel for short stays in the EU's Schengen area which comprises 22 EU and four non-EU members.
However, the EU wants Turkey to narrow its broad definition of terrorism to match tighter EU standards. It is one of five EU criteria Turkey still has to agree to in order to meet the visa-free requirements.
Mr Erdogan rejected this, saying in a televised speech on Friday: "Turkey, when it's under attack from terrorist organisations from all sides, the European Union is telling us to change the anti-terror law in exchange for the visa deal."
Referring to tents erected by the outlawed Kurdistan Workers' Party, or PKK, near the EU parliament in Brussels, Mr Erdogan said: "You [the EU] will let terrorists build tents and provide them with opportunities in the name of democracy.
"And then [you] will tell us 'if you change this [anti-terrorism legislation], I will lift the visas'. Sorry, we'll go our way, you go yours."
BBC Turkey correspondent Mark Lowen says Mr Erdogan's hard rhetoric will please his support base but will alarm European leaders.
In recent months, he says, the government has used the terms "terrorist" or "terrorist supporter" to prosecute critics including journalists, suggesting they are supporting Kurdish militants or other armed organisations.
If Mr Erdogan does not meet the EU requirements, the European Parliament and EU leaders will not vote on the visa waiver at the end of June and, our correspondent says, the whole deal could fall apart.
Key points of Turkey-EU agreement
- Returns: All "irregular migrants" crossing from Turkey into Greece from 20 March will be sent back. Each arrival will be individually assessed by the Greek authorities
- One-for-one: For each Syrian returned to Turkey, a Syrian migrant will be resettled in the EU. Priority will be given to those who have not tried to illegally enter the EU and the number is capped at 72,000
- Visa restrictions: Turkish nationals should have access to the Schengen passport-free zone by June. This will not apply to non-Schengen countries like Britain. Turkey must meet certain criteria
- Financial aid: The EU is to speed up the allocation of €3bn ($3.3 bn; £2.3 bn) in aid to Turkey to help migrants.
- Turkey EU membership: Both sides agreed to "re-energise" Turkey's bid to join the European bloc, with talks due by July.
Another part of the EU-Turkey deal had been to hold new talks on Turkish accession to the EU.
But analysts say Mr Erdogan has been less convinced of EU alignment than Mr Davutoglu, and he will certainly be a tougher negotiator.
On Thursday, Mr Davutoglu, who was hand-picked by Mr Erdogan to succeed him as head of the governing AK Party after Mr Erdogan was elected president in 2014, said he would not stand again as leader at an extraordinary party congress called for 22 May.
Our correspondent says Mr Davutoglu had not been the pliant PM Mr Erdogan had hoped for, and the resignation is a tightening of control by the president.
Five benchmarks still to be met by Turkey:
- Corruption: Turkey must pass measures to prevent corruption, in line with EU recommendations
- Data protection: It must align national legislation on personal data protection with EU standards
- Europol: An agreement is to be concluded with the continent's law enforcement agency
- Judicial cooperation: It must work with all EU members on criminal matters
- Legislation on terrorism: Turkey is also required to bring its terror laws in line with European standards
The prime minister's unease with Mr Erdogan's plans to move to a presidential system, among other policies, had been evident in recent months.
In his speech, Mr Erdogan dismissed those who believe that, as president, he should stand aside from party politics.
He expressed his determination to put presidential reform to a referendum as soon as possible.
He said: "The presidential system issue is not Recep Tayyip Erdogan's personal request. The place in which Turkey has arrived as a result of its experiences has created an urgent need for both the presidential system and the new constitution."
Among those tipped as successors to Mr Davutoglu are Transport Minister Binali Yildirim, who is close to Mr Erdogan, and Energy Minister Berat Albayrak, who is the president's son-in-law.