Turkey's state television cut off live broadcasting on Tuesday when the head of the largest pro-Kurdish party began addressing his parliamentary deputies in the Kurdish language.

The incident highlights tensions in the European Union-candidate country over the public use of the once-banned language despite recent government moves to ease restrictions, including launching a Kurdish state channel.

It also comes ahead of March 29 local elections, in which the ruling AK Party is locked in a close battle with the pro-Kurdish Democratic Society Party (DTP) in Diyarbakir, the largest city in the Kurdish southeast region.

"In order to show that there is nothing to fear in using other languages and to emphasize brotherhood of languages during the International Day of Mother Tongues, let me continue my speech in Kurdish," DTP head Ahmet Turk told a gathering of DTP members before he went off the air.

State owned TRT channel said it had cut off Turk's speech because under Turkey's constitution, Turkish is the official language of Turkey. It apologized to its viewers.

Turkey launched a Kurdish state channel in January to expand cultural rights of minority Kurds.

However, some restrictions on Kurdish remain in place, including giving political speeches, Reuters reports.