Danish police were investigating a plane at Copenhagen airport due to depart for Istanbul, in response to a threat against aircraft of Turkish airline Atlasglobal in Europe, the airport said on Monday.
The suspects had previously been involved with Islamic State group extremists in "conflict zones", state-run news agency Anadolu said without giving further detail.
Itir Esen, 18, won Miss Turkey 2017 during a ceremony in Istanbul on Thursday night and was going to represent the country in the Miss World competition in China.
Thousands of supporters of a conservative Turkish party rallied in Istanbul on Sunday to protest measures taken by Israel in Jerusalem and show solidarity with the Palestinians.
Heavy rainfall hit Istanbul on Tuesday, flooding streets and causing disruption to public transport, officials and AFP correspondents said.
An external battery pack caught fire on Thursday at Istanbul's Ataturk airport after an angry passenger threw the object because of an electronic devices ban on flights to the UK, the airport operator said.
Turkey's mass-circulation daily Sozcu printed an entirely blank edition on Saturday after two of its journalists were detained in police raids.
Istanbul authorities have withdrawn an invitation to Wikipedia founder Jimmy Wales to attend a major conference in the city, officials said on Tuesday, after Turkey blocked access to the online encyclopaedia.