The co-leader of Turkey's main Kurdish party on Thursday dismissed air strikes and police raids by Ankara against Islamic State (IS) jihadists as a "show", saying their real target was Kurdish militants.

In an interview with Agence France-Presse, Selahattin Demirtas of the Peoples' Democratic Party (HDP) said the peace process between Turkey and Kurdish militants was now "in deep crisis" due to the offensive by Ankara against the separatist rebels but insisted it should not be written off.

Turkey has launched a two-pronged offensive against IS jihadists and Kurdistan Workers' Party (PKK) militants but the strikes against the Kurdish rebels have been far the more frequent and intense.

Demirtas accused the government of President Recep Tayyip Erdogan of using strikes against IS as "cover" for its main goal of striking the PKK and weakening the HDP's major electoral gains.

"A few air raids were launched by Turkey against IS targets for show only and it is over," he said.

"So-called IS suspects were detained with a few operations for show and most of them were released," he said.

According to figures from the Turkish government, around one tenth of those arrested in raids against suspected militants were IS-linked and the rest largely Kurdish.

Demirtas said that the air strikes on IS were "used as cover" for the far more extensive bombings of PKK positions.

For almost a week, Turkish army jets have pounded Kurdish militant targets inside Turkey and in neighbouring northern Iraq.

Demirtas accused Erdogan of harming the peace process by equating IS with the PKK, two groups who are themselves vehemently opposed.

"This (the peace process) was going to be settled," before the Turkish air offensive, said Demirtas, adding that Erdogan was trying to put the PKK and IS on the "same scale".

The PKK, designated as a terrorist organisation by Ankara and its Western allies, had until now largely observed a truce declared by its jailed leader Abdullah Ocalan in March 2013.

- 'Orchestrated crisis' -

Demirtas accused Erdogan of orchestrating the crisis in the hope of bolstering his own powers after the ruling party's lacklustre performance in the June 7 legislative election when it lost its overall majority.

He said the military operations were a manoeuvre to oust the HDP from parliament in a snap poll and impose effective one-party government.

"This war is not waged to protect our country's soil but to protect the future of the Palace," Demirtas said, referring to Erdogan's controversial and costly new presidential palace which has been bitterly criticised by the opposition.

The HDP scored a political breakthrough in the election, easily breaking through the 10 percent threshold and taking 80 seats.

Demirtas said the ruling party wanted to force the HDP under the threshold in new elections, robbing it of all its seats and allowing the AKP to recapture its majority.

Erdogan has repeatedly accused the HDP of being a front for the PKK but Demirtas dismissed any such links.

In a fierce personal attack on him during his visit to China, Erdogan told Dermirtas to "know his place" and referred to the presence of his elder brother Nurettin among the PKK fighters in Iraq.

"He (Demirtas) is a person whose elder brother has obviously been raised in the mountains," said Erdogan, referring to the PKK's Iraq bases. "He would run there if he found the opportunity."

But Demirtas dismissed the charges. "We are definitely not a party of the PKK, nor its political wing," he said. "We are two separate groups."

He said he did not have any personal problem with Erdogan but only opposed his "incorrect policies".

"If this causes him personal frustration, it is his problem. It appears his psychology is not in good state."

- 'Peace process in crisis' -

Demirtas said that the peace process was in trouble but insisted it was not over.

"The peace process right now is going through a deep crisis."

"But to say the process is over is against the spirit of peace. Peace will come sooner or later."

Demirtas said the "weapons must be silenced" by both sides immediately so that conditions can be created for a return to talks.

Erdogan said this week it was "not possible" to continue the peace process so long as the PKK was attacking Turkish targets.

On his the fate of his brother, Demirtas said: "I don't even know if he's dead or alive. I have not received any news."