The EU is preparing an additional 500 million euros in aid for Syrian refugees in Turkey to ease tensions with Ankara, European sources told AFP on Thursday. The funding offer comes after EU officials accused Turkey of "blackmail" by opening its border with Greece last week to thousands of refugees trying to reach Europe. The spat had raised the spectre of a repeat of the 2015-2016 migrant crisis. The money will be in addition to the six billion euros allocated in 2016 to finance programmes to support roughly 3.6 million Syrian refugees in Turkey. That was part of an EU-Turkey deal that dramatically cut the flow of migrants crossing the Aegean Sea to Greece. Turkish President Recep Tayyip Erdogan said on Monday he had already rejected an EU offer of one billion euros. "They tell us, 'we will send you a billion euros.' Who are you trying to fool? ... We don't want this money," he said. Turkey has yet to react to the latest offer. The commission, the EU's executive arm, will also propose to facilitate visas for Turkish nationals heading to Europe. The EU's foreign policy chief Josep Borrell meanwhile announced on Wednesday the release of 170 million euros in emergency aid "for the most vulnerable in Syria" during his visit to Ankara. Rights groups have accused Turkey of using migrants as bargaining chips by pushing them towards the Greek border. But they also condemned Europe for failing to provide greater assistance. Thousands have arrived at the frontier since Erdogan announced that Turkey would no longer stop them trying to enter the European Union. Erdogan has repeatedly bemoaned a lack of support from Europe for his military incursions into Syria, where Turkish troops are fighting against Russia-backed Syrian government forces. bur/arp/jxb