Turkish police on Thursday detained the pro-Kurdish co-mayor of the southeastern city of Van in the latest raids targeting municipal chiefs, expanding a widespread crackdown that has sparked international concern.

Bekir Kaya was taken into custody as part of a "terror investigation", the official news agency Anadolu reported, saying he was accused of membership of the outlawed Kurdistan Workers' Party (PKK).

If found guilty, he could face up to 15 years in jail, it said.

The targeting of city heads follows the arrest of 10 MPs from the pro-Kurdish Peoples' Democratic Party (HDP), including its co-leaders, who are being held on charges of links to the PKK in a crackdown that has caused international alarm.

On Wednesday, mayors in the southeastern city of Siirt and the eastern city of Tunceli were detained following similar accusations of links to the PKK, Anadolu said.

And last month saw the arrest of the two mayors of the mainly Kurdish city of Diyarbakir.

Gultan Kisanak and Firat Anli have been charged with "belonging to an armed terrorist organisation" and providing "logistical support to an armed terrorist organisation" -- the PKK.

All the mayors were elected in the 2014 local elections.

EU visit cancelled

Turkey declared a state of emergency following a failed coup on July 15, arresting tens of thousands of people as part of a widespread crackdown which critics say has gone well beyond the alleged plotters to include anyone daring to criticise President Recep Tayyip Erdogan.

EU and US officials have expressed concern over the arrest of opposition lawmakers as fears grow over Turkey's use of emergency laws.

In a sign of the tensions with the West, top EU lawmakers on Wednesday cancelled a visit to Turkey in a dispute over the format of the trip.

The crackdown comes as Ankara wages a relentless battle to crush the PKK, which has stepped up attacks since the collapse of a two-and-a-half-year ceasefire in July 2015.

Hundreds of Turkish security forces have been killed in clashes and attacks while thousands of militants have been killed, according to Anadolu figures.

The PKK has waged an insurgency inside Turkey since 1984 and is proscribed as a terrorist group by both Washington and Brussels.

Caretakers appointed

Government-appointed trustees have been named to replace all the detained mayors, the interior ministry said in a statement.

The move is controversial given that the mayors are all directly elected and only provincial governors are appointed by the government.

In Van, Kaya was suspended and replaced by city governor Ibrahim Tasyapan as municipality administrator, an interior ministry statement said.

In the southeastern city of Mardin, mayor Ahmet Turk was suspended and replaced by the city governor, while Siirt mayor Tuncer Bakirhan was also replaced by the city's deputy governor, the ministry said.

And Tunceli has been placed in the care of deputy regional governor Olgun Oner.

Like many mayors in the majority-Kurdish southeast, Kaya worked with a female co-mayor in a policy spearheaded by the HDP to promote gender equality.

Van, situated on a beautiful lake and whose history dates back to the Urartu kingdom three millennia ago, is one of the key tourist destinations of the Turkish southeast and increasingly popular with visitors from neighbouring Iran.