Dozens of couples have locked lips at a subway stop in Turkey's capital, Ankara, to protest subway authorities' admonishment of a couple that kissed in public.

Some 100 people in the station kissed for several minutes in protest on Saturday. Demonstrators carried signs reading "Free Kisses'' and chanted slogans.

Turkish media reported that, earlier in the week, Ankara subway officials made an announcement asking passengers "to act in accordance with moral rules" after security cameras spotted the couple kissing.

The issue prompted an opposition lawmaker to question the ruling party, which many secularists fear wants to expand the role of Islam in Turkey, about whether subway officials were authorised to make such demands.

A conservative group of some 20 people staged a counter-protest. Police set up barricades between the groups.