The Turkish parliament has approved a controversial bill that will strip MPs of their immunity from prosecution.
Pro-Kurdish lawmakers say this is essentially a move to expel opposition members from parliament.
The measure is seen as targeting the pro-Kurdish Peoples' Democratic Party (HDP) as well as the main opposition Republican People's Party (CHP).
A ceasefire ended weeks after elections in June 2015. The renewed conflict has claimed hundreds of lives on both sides, particularly in the south-east.
President Recep Tayyip Erdogan accuses the HDP of being the PKK's political arm, and has called for pro-Kurdish MPs to face terrorism charges.
This vote could be a first step towards making that happen.
Calling the move "historic" as lawmakers voted, Mr Erdogan told a crowd in his hometown of Rize: "My people do not want to see guilty lawmakers in this parliament."
'Blow to people's will'
Critics also say the move aims to strengthen the ruling AK Party and consolidate support in the assembly for the executive presidential system Mr Erdogan wants to implement.
HDP co-leader Selahattin Demirtas said it was a blow against the people's will and could not be accepted as democratic.
He said the party would challenge the decision at Turkey's top court.
A dangerous moment: Mark Lowen, BBC News, Ankara
The pro-Kurdish HDP party says the government is using trumped-up charges to push their party out of parliament and allow President Erdogan to change the constitution and boost his own powers.
The government rejects that claim, saying MPs should be accountable before the law. In a country with faith in its democracy and judicial independence, that would be the accepted view.
But in Turkey there are deep misgivings about both and Mr Erdogan is seen by critics as increasingly authoritarian - hence the concerns.
If several HDP MPs are arrested, there are fears it could spark worse violence in Kurdish areas, where people could feel deprived of a voice in parliament. And so this is a dangerous moment for Turkey and a test of how far Mr Erdogan is willing to go to secure his position.
The bill was backed by 376 MPs in the 550-seat legislature in the third and final vote of a secret ballot.
This means it will become law directly without being put to a referendum. It now needs to be ratified by the president.
Some 138 lawmakers, the vast majority from the two opposition parties, could be at risk of prosecution.
Violent scuffles marred parliamentary debates this month, with frustrated lawmakers exchanging fisticuffs and kicks.
Friday's vote was not without incident as CHP lawmakers walked out in protest.
German Chancellor Angela Merkel's spokesman said she would raise concerns over the state of democracy in Turkey when she met Mr Erdogan next week.
Mrs Merkel, who has led the push to conclude a migrant deal with Ankara, has been criticised by human rights groups for turning a blind eye to violations in Turkey in return for co-operation.
One of the most disputed issues is about Turkey's refusal to comply with EU demands to narrow anti-terror laws, accused of being used to intimidate journalists and stifle dissent.
The government denies it, saying it needs the laws to fight militants.