BRUSSELS: Turkey defied pressure from the European Union on Thursday to amend its anti-terrorism laws, saying that a suicide bomb attack at Istanbul airport this week that killed 42 people provided further vindication of its tough stance.

But Turkish officials, in Brussels for further talks on their country's decades-long bid to join the EU, also argued that the bloc needed Turkey, with its economic and geopolitical weight, more than ever after Britain's vote last week to leave.

The EU repeated its demand that Turkey modify its anti-terrorism laws, saying they limit freedom of expression and allow indiscriminate arrests of activists, but Ankara showed no sign of budging.

"Turkey today is fighting against terrorism," Turkish Foreign Minister Mevlut Cavusoglu told a joint news conference with senior EU officials, referring to Tuesday's gun and bomb attack by three suspected Islamic State militants.

"New demands directed at Turkey would encourage terrorists. We cannot make any changes in our anti-terror laws," he said.

Turkish police have detained 13 people, three of them foreigners, in raids across Istanbul in connection with the attack, the deadliest in a series of suicide bombings in Turkey this year.

The EU has tied the changes in the anti-terrorism laws to progress in Turkey's bid to win for its citizens the right to travel in Europe without visas. That right is part of a bigger deal whereby Turkey also promises to take back Syrian and other migrants who leave its shores for the EU.

"FRESH VISION" NEEDED

Turkey, a NATO member strategically located between Europe and the Middle East and boasting a vibrant economy and young population, will be a great asset for the EU, the country's EU minister Omer Celik said in Brussels.

"Turkey is a major European power ... Europe needs a fresh start and a fresh vision and will have to include Turkey," he said, referring to Britain's decision to leave, or 'Brexit'.

"Whatever the picture will be after Brexit, Turkey's position will be stronger. Any picture that doesn't include Turkey will be a weak picture."

Ironically, Britain had long been Turkey's main advocate in the EU, often in the face of deep German and French scepticism.

But Britain's referendum 'leave' campaign successfully tapped into Britons' fears of large-scale immigration, including from Muslim Turkey. Prime Minister David Cameron, struggling to persuade his compatriots to vote to remain in the EU, even suggested Turkey might not join until the year 3000, causing consternation in Ankara.

In another role reversal, German Chancellor Angela Merkel reluctantly agreed to back an acceleration in Turkey's EU bid because she needs Ankara's help in stemming the flow of migrants after more than one million arrived in Germany last year.

This month EU officials have taken Ankara to task not only over its anti-terrorism laws but also over its arrest of three press freedom campaigners, amid deepening unease about the human rights situation in Turkey under President Tayyip Erdogan.

"We have to act within the limits of the rule of law and defend our freedom of expression. This is not something we can give up or suspend," EU Enlargement Commissioner Johannes Hahn told Thursday's news conference.

In a small victory for Turkey, the EU opened negotiations on Thursday on EU budget payments, one of 35 policy areas or chapters in the country's accession process.

But Slovakia, which takes over the EU's rotating six-month presidency on Friday from the Netherlands, played down Turkish hopes for more swift progress in the negotiations which began in 2005 but have only edged forward very slowly.

"I would like to open more chapters during our presidency but honestly I don't see the consensus," Slovak Foreign Minister Miroslav Lajcak told reporters in Bratislava.