Dozens of Turks sneak into Europe in passport scam
The scandal has dominated local headlines since it emerged last week that 43 people with grey service passports entered Germany last November to attend an environmental workshop and never returned to Turkey.
Grey passports are issued to people working abroad for the state, allowing visa-free travel to many countries.
They were sent by a local district municipality in the eastern province of Malatya, according to local media.
The interior ministry in a statement on Monday said the probe would be widened to include six more local municipalities in cities including Ordu on the Black Sea.
The six included ruling and main opposition party mayors.
They had sent individuals for "folk dance shows, culture tours, youth programmes" in cooperation with non-governmental organisations, the interior ministry said.
It also temporarily suspended issuing service-stamped passports for non-public sector employees who were assigned to work abroad by local authorities.
Last week, the ministry suspended the deputy governor of Malatya, two public officials and the provincial head of the population and citizen affairs body over the scandal.
One source told HaberTurk website how people paid 6,000 euros ($7,200) for the passport to go to Germany through Bingol municipality in eastern Turkey.
They also claimed at least "450-500" people went to Europe using this method.
In a video posted online by Anka News Agency, the main opposition party mayor of Yesilova in southwestern Turkey said the claims relating to his district dated back to 2018, before he was elected.
Mumtaz Senel said 387 people were sent to Rome with grey passports but 23 never returned their passports.