(Adds background, jailing of co-leader, HDP reaction)
ANKARA, Feb 21 (Reuters) - Turkey's parliament on Tuesday stripped one of the pro-Kurdish Peoples' Democratic Party's (HDP) two leaders of her status as a member of parliament and jailed the other, weeks ahead of a referendum on extending the president's powers.
Figen Yuksekdag has been in detention on terrorism charges since November after being arrested with co-leader Selahattin Demirtas and, on Tuesday, Demirtas was sentenced to five months in jail, broadcaster NTV and other media reported.
HDP lawmaker Idris Baluken has also been arrested, NTV said.
The arrests have left the second-largest opposition party leaderless before Turks vote on April 16 to replace Turkey's parliamentary system with an executive presidency.
The HDP, which says as many as 5,000 of its members have been detained, opposes the changes, which, if passed, could see President Tayyip Erdogan rule until 2029.
Erdogan and his supporters say the changes will give Turkey stronger leadership. But his critics, including the HDP and main opposition secular CHP, say it will lead to a one-man rule and erode basic freedoms.
The HDP tweeted its rejection of Yuksekdag's ban as "non-existent". On Monday, it appealed to the European Court of Human Rights over what it said was the unlawful imprisonment of its two leaders on terrorism charges.
Prosecutors want Demirtas jailed for 142 years and Yuksekdag for up to 83 years on the charges of inciting violence and propaganda in support of a terrorist organisation. Demirtas was sentenced on Tuesday for "insulting the Turkish people, the government of the Turkish Republic, and state institutions".
Their arrests, along with tens of thousands of others since an abortive putsch in July, drew international condemnation over what rights groups say is a widening crackdown on dissent.
Erdogan and the government, however, say the HDP is an affiliate of the militant Kurdistan Workers Party (PKK), which has waged an armed insurgency in Turkey's largely Kurdish southeast for more than three decades. The HDP denies direct links to the PKK, which is considered a terrorist organisation by Turkey, the United States and the European Union.
Since the failed coup, some 40,000 people have been arrested and more than 100,000 have been sacked or suspended from the military, civil service and private sector. (Reporting by Ercan Gurses; Writing by Tuvan Gumrukcu; Editing by Louise Ireland)