Turkish President Tayyip Erdogan said on Tuesday comments at the weekend from the leader of the pro-Kurdish Peoples’ Democratic Party (HDP) were a “clear provocation” and the party “will be taught a lesson” by the people and the law.

Erdogan’s broadside at HDP chief Selahattin Demirtas could further widen the gulf between the government and the Kurdish opposition. A Turkish prosecutor opened an investigation into Demirtas after he made calls for greater Kurdish self-governance, Dogan news agency reported on Monday.

“A certain leader … talked nonsense and what he did is clear provocation and treason,” Erdogan told reporters in Istanbul before departing on a trip to Saudi Arabia, adding that the HDP would be “taught a lesson by our citizens and the law”.

Demirtas was a participant in a two-day congress of Kurdish groups this weekend that called for more self-governance. At the conference, he said there would be a Kurdistan in the next century and it could include an independent state.

Turkey’s government is opposed to a separate Kurdish state.

There is an autonomous Kurdish entity known as the Kurdistan Regional Government (KRG) in neighbouring northern Iraq.

Violence in Turkey’s mainly Kurdish southeast has flared up since the collapse of ceasefire in July. Fighting has been particularly intense in the last two weeks and the military says more than 210 Kurdish militants have been killed.

The HDP says civilians are also dying, something the government denies.