Turkey's main opposition on Monday threatened an unspecified protest action in parliament over two newly-elected lawmakers who are kept in jail as part of a coup trial.
"All options are on the table... Blocking the parliamentary system is something the Republican People's Party (CHP) would never wish for but we will not bow down to injustice," CHP deputy chairman Engin Altay said on NTV television.
"As long as our colleagues remain in prison, the parliament's legitimacy will be open to debate," he warned.
Turkey's new parliament is set to convene Tuesday for an oath-taking ceremony following the June 12 elections, in which the Islamist-rooted Justice and Development Party (AKP) won a third straight term in power.
Some 30 Kurdish-backed lawmakers already announced last week they would boycott the legislature after one of them was stripped of his seat amid a legal controversy over a terror-related conviction.
Defying precedents, judges also rejected pleas to release popular journalist Mustafa Balbay and prominent academic Mehmet Haberal, who were elected on CHP ticket while in prison, charged with involvement in plots to overthrow the AKP.
Lawyers had sought their release on grounds that the suspects, detained for more than two years, do not pose a risk of destroying evidence or fleeing the ongoing trial.
The CHP, Altay said, will convene Tuesday ahead of the parliament's opening session, to decide its next step.
A protest action will go ahead unless the courts reverse their rulings to keep Balbay and Haberal in jail, or the AKP, which dominates parliament, promises a legal amendment to secure their release, he said.
Seven other people, including Kurdish politicians, were elected to parliament while awaiting trial in prison. They were all denied release.
The coup probe that landed Balbay and Haberal in jail is already facing criticism that it has degenerated into a government-backed campaign to bully AKP critics.