The US-based newspaper the Wall Street Journal has denounced a jail sentence handed to one of its reporters by a Turkish court.

A Turkish court sentenced Ayla Albayrak on Thursday to a prison term of two years and one month over a 2015 story about ongoing clashes between Turkish security forces and fighters from the outlawed Kurdistan Workers' Party (PKK) in the southeast of the country, according to a report by the newspaper.

The court ruled that she had shown support for the outlawed PKK group in the article, accusing her of "terrorist" propaganda.

Albayrak, who has dual Turkish and Finnish citizenship, is currently in the United States and will appeal against the conviction, the Wall Street Journal said.

Turkey, the US and the EU consider the PKK a "terrorist organisation".

The court decision coincides with an escalating fight between Turkey and the US after the NATO allies mutually suspended visa services on Sunday, plunging already strained relations to a new low.

Albayrak's story featured interviews with the town mayor and residents, a Turkish government official, and a representative of an organisation Turkey says is the PKK's youth wing, the newspaper said.