Istanbul (AFP) - A car bomb exploded Monday outside the provincial HQ of the ruling Justice and Development Party (AKP) in the eastern Turkish city of Van, wounding more than 50 people, including four police, local authorities said.

Turkish officials blamed the outlawed Kurdistan Workers' Party (PKK), which has waged a three-decade insurgency against the Turkish state and is considered a terrorist group by Ankara and its Western allies.

The attack took place near a police checkpoint outside the party building, located in the heart of the city, the local governor's office said in a statement.

A car "was blown up by members of the separatist terror organisation", it added, using a term to describe Kurdish militants.

Local governor Ibrahim Tasyapan said at least 53 people including four police officers were wounded in the attack, adding that the bomb was detonated by remote control.

CNN-Turk television reported that some Iranian tourists in the bustling city were among the injured.

There was no immediate claim of responsibility for the bombing, which came on the first day of the Muslim holiday of Eid Al-Adha.

But Besir Atalay, an AKP lawmaker from Van, pointed the finger of blame at the PKK.

"The terrorist organisation has targeted our party building and the AKP's presence in the past. This is one of their attacks," he added, in live comments on the private NTV television.

Witnesses said the blast shattered windows in the vicinity and the AKP's provincial offices sustained severe damage.

Several ambulances rushed to the scene and television images showed water cannon being used to douse a fire.

Van, a city with a mixed Kurdish and Turkish population on the shores of the lake of the same name, has generally been spared the worst of attacks like those seen in the nearby city of Diyarbakir.

The city is a popular tourist destination, particularly with Iranians who arrive from across the border in huge numbers to enjoy shopping and the relaxed atmosphere.

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- 'Disgraceful'-

The US embassy in Ankara condemned what it called a "terrorist attack", adding that such criminal acts were never justified.

"The fact that the terrorists struck on the first day of the Sacrifice Holiday is particularly disgraceful," the embassy said in a statement.

The blast came a day after the government announced the removal of 28 mayors, mainly over alleged links to the PKK in a move strongly denounced by pro-Kurdish parties.

President Recep Tayyip Erdogan defended the suspension of the mayors, saying it was a long-overdue move.

"You, as mayors and municipal councils, cannot stand up and support terrorist organisations," he told reporters after prayers outside an Istanbul mosque, shortly before the attack.

The government has also stepped up its military campaign in the restive southeast to eradicate PKK militants, who have launched almost daily attacks since a fragile ceasefire ended last year.

In a message relayed by his brother, jailed PKK leader Abdullah Ocalan said the Kurdish conflict could be settled if the state was ready.

"He said if the state is ready for the projects we can implement them in six months," Mehmet Ocalan said in Diyarbakir, without offering further details.

Mehmet Ocalan also said his brother was in "good health" amid concerns over the jailed leader's welfare after months cut off from the outside world on Imrali prison island near Istanbul.

He met with the PKK leader at his island prison at the weekend -- the first family visit in two years.

A group of 50 Kurdish activists including MPs announced on Monday they were ending their hunger strike on the eighth day, after receiving news on Ocalan's health through his brother, a spokeswoman for the group said.

Tens of thousands of people have been killed since the PKK first took up arms in 1984, with the aim of carving out an independent state for Turkey's Kurdish minority.

Turkey has also launched an operation inside Syria to remove Islamic State (IS) group militants as well as Syrian Kurdish militia from its frontier.