The leader of Turkey's Nationalist Movement Party (MHP) spoke of his sadness on Thursday over the deaths of three soldiers -- a day after opponents said his party would be held responsible for future deaths after it opposed an inquiry into recent attacks.Republican People's Party (CHP) lawmaker Fikri Sağlar said on Wednesday the MHP would be held to account "for any deaths from now on" after its deputies sided with the Justice and Development (AK Party) to vote down a motion calling for a parliamentary inquiry into the attacks that have hit Turkey since the July 20 bombing in Suruç.The Peoples' Democratic Party (HDP) voted alongside the CHP."This sad news proves once again how wrong it was for the Republican People's Party and Peoples' Democratic Party to collaborate in parliament yesterday, calling for extra measures against terrorist threats," Bahçeli told reporters after a party meeting in northern Tokat province. He gave no further explanation of his comments.The soldiers were killed in southeastern Şırnak province Thursday in an ambush blamed on the PKK terrorist organization.Bahçeli has been outspoken in recent days, attacking the pro-Kurdish HDP's leader Selahattin Demirtaş for his failure to condemn attacks by the PKK."I am calling on the CHP not to yield to the provocations of its HDP-leaning members," Bahçeli said.There have also been calls for Demirtaş to be stripped of his parliamentary immunity. The HDP's response was to submit a motion to parliament waiving immunity for all its 80 lawmakers and to call on other parties to follow suit.Commenting on a potential vote on HDP deputies' immunity, Bahçeli said the MHP "knows what to do when the day comes".Security forces have been targeted in a wave of deadly attacks, mostly in Turkey's Kurdish-majority regions, since 32 activists were killed in Suruç in a bombing linked to ISIS.More than 1,300 suspected supporters of ISIS, the PKK and leftist groups have been arrested in the aftermath, according to the government, and Turkey has also launched airstrikes against ISIS and PKK positions in Syria and Iraq.