ANKARA (Reuters) - Turkish authorities arrested three academics on charges of “terrorist propaganda” on Tuesday after they publicly read out a declaration reiterating a call to end security operations in the mainly Kurdish southeast.

Police also detained a British national at the courthouse that ordered the arrests after finding him with pamphlets printed by parliament’s Peoples’ Democratic Party (HDP), which has Kurdish roots.

The government blames the Kurdistan Workers Party (PKK) for a car bombing in the capital on Sunday that killed 37 people. The PKK, which has waged a decades-long insurgency, is linked with another bomb attack in Ankara in February that killed 29.

More than 2,000 academics signed a petition in January criticizing military action in the southeast, including round-the-clock curfews aimed at rooting out PKK militants who have barricaded themselves in residential areas in southeastern cities.

Hundreds of civilians, security forces and militants have been killed since the conflict with the PKK reignited in July in the worst violence Turkey has seen for 20 years.

The petition outraged President Tayyip Erdogan, who said the academics would pay a price for their “treachery”.

Lawyers said Esra Mungan, Muzaffer Kaya and Kivanc Ersoy were detained after they held a news conference on March 10 and criticized the pressure those who signed the petition have faced, including dozens of dismissals from university posts.

The court ruling said they had not mentioned the PKK in their declaration, which amounted to tacit agreement with its actions, according to a copy provided by one of their lawyers.

The PKK is designated a terrorist group by Turkey, the United States and the European Union.

Chris Stephenson, a British citizen who teaches at Bilgi University, was detained outside the Istanbul courthouse where he had come to show support for Mungan, Kaya and Ersoy.

“I am accused because I had several invitations to Kurdish new year (celebrations on March 21) published by the HDP - the third-largest party in the Turkish parliament - in my bag,” Stephenson wrote on Facebook, saying he would be held overnight.

Erdogan said on Monday the definition of a terrorist needed to be broadened to include supporters, listing lawmakers, academics, journalists or civil society leaders as examples.

Erdogan has previously accused the HDP of being an extension of the PKK, calling for legal action against lawmakers.